FOUS11 KWBC 181910
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
310 PM EDT Wed Mar 18 2026

Valid 00Z Thu Mar 19 2026 - 00Z Sun Mar 22 2026

...Upper Midwest to the Northeast...
Days 1-3...

A quiet pattern with respect to heavy snow and icing will continue,
with widespread heavy snow or significant icing not expected across
the contiguous U.S. through the end of the week.

Precipitation associated with a low-amplitude shortwave sliding
southeast across the Upper Midwest is expected to produce some
minor ice accumulations tonight from northern Wisconsin southeast
into southern Michigan and far northern Indiana.

Meanwhile, a more amplified shortwave to the north will spread
light snow from far northern Michigan to Upstate NY and northern
New England as it swings across southeastern Canada on Thursday.

A second shortwave will amplify over the northern Great Lakes on
Friday and move east across the Northeast on Saturday, bringing
additional light snow accumulations to the same regions. Apart
from some localized heavier amounts in the higher reaches of the
Adirondacks and the northern New England mountains, three-day snow accumulations are expected to top out at only an inch or two for
most of the impacted locations.

Pereira

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FOUS11 KWBC 190611
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
211 AM EDT Thu Mar 19 2026

Valid 12Z Thu Mar 19 2026 - 12Z Sun Mar 22 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

Thanks to a dome of upper-level ridging firmly entrenched over
the West and northerly low-level winds over the Mid-South all but
cutting off Gulf moisture, a quiet pattern with respect to heavy
snow and icing will continue. The lone cases where light snow
accumulations are anticipated are across the Upper Great Lakes and
Northeast as Canadian clipper systems race across the southern
tier of the country and occasional pass through. A clipper over
Ontario will direct a warm front through the Northeast with minor
snowfall totals (generally a coating-2", with local 2-3" in the
Adirondacks and White Mountains) through Thursday. As that system
exits over Atlantic Canada, a more organized clipper will be
tracking towards Lake Superior. Light snow will ensue along the
warm front over the U.P. of MI, Thursday night and into Friday AM,
then race over northern NY and northern New England Friday
afternoon and evening.

There are some hints in AI guidance (EC-AIFS most notably) that the
clipper could strengthen by the time it reaches Downeast Maine
early Saturday morning. This could lead to locally heavier snowfall
in the Greens, Whites, and northern ME on Saturday. At the moment,
WPC probabilities shows low chances (10-30%) chances for snowfall

4" in northern ME with most snowfall generally under 3". But this

will be closely monitored given the generally good performance of
the EC-AIFS for much of the cold season.


The chances for significant icing across the CONUS is less than 10
percent.


Mullinax




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FOUS11 KWBC 191903
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
303 PM EDT Thu Mar 19 2026

Valid 00Z Fri Mar 20 2026 - 00Z Mon Mar 23 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

Ridge/trough upper pattern over the CONUS will continue to bring
northern stream systems through the Great Lakes into the Northeast
with minor to occasionally modest snowfall. A system over southern
Canada this evening will push through the Great Lakes tonight and
into southern/southeastern Ontario tomorrow. WAA-driven snow and
some light icing is likely over the U.P. of Michigan and into
northern Lower Michigan. As the clipper moves into the Northeast
tomorrow afternoon/evening, snow will fall mostly over the higher
elevations (above 1500ft or so) where WPC probabilities for at
least 4" are >50%, with lesser accumulations to the valley floors
(T-2"). Precipitation should end on Saturday morning.

The next system will slip into northern MN and the western Great
Lakes Saturday afternoon/evening. With a southwest-to-northeast
thermal gradient, some icing is possible once again over
northeastern MN, northern WI, and northern Lower Michigan near the
surface warm front. That system may track a bit farther south,
which could bring in at least some light to modest snow to
northeastern MN into the U.P. of Michigan. There, WPC probabilities
for at least 4 inches of snow are >40% Saturday into very early
Sunday. The system will race eastward and bring another swath of
snow to northern NYS into New England Sunday. Through 00Z/Mon, WPC probabilities for an additional 4 inches of snow are >30% over the
higher elevations of the northern Adirondacks into the Green/White
Mountains, but the snow will continue beyond this forecast range.


The chances for significant icing across the CONUS is less than 10
percent.

Fracasso

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FOUS11 KWBC 200701
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
301 AM EDT Fri Mar 20 2026

Valid 12Z Fri Mar 20 2026 - 12Z Mon Mar 23 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

The first in a series of clipper systems will produce periods of
snow across northern New York and northern New England today. Low-
level WAA ahead of the clipper will support periods of snow, even
down to the valley floors in northern New England. However,
snowfall rates and elevation will play critical roles in snowfall accumulations. Most notably, the Adirondacks, Green, and White
Mountains are most favored for >1"/hr snowfall rates. WPC
probabilities depict localized moderate probabilities (40-60%) for
snowfall totals >4" with the peaks of these mountain ranges
(including Mt. Washington) sporting low chances (10-30%) for
snowfall accumulations as high as 6". Otherwise, most elevations
below 1,000ft are likely to see anywhere from a coating to as much
as 3". The WSSI does depict some Minor Impact potential,
particularly in the Adirondacks and bordering the St. Lawrence
River in NY's North Country. Snow will taper off across northern
New England by Friday night.

As this clipper exits to the east Saturday morning, the next
clipper system is already making its way towards the Upper Great
Lakes. There remains a decent amount of model spread in the
amplitude and progression of this clipper, largely because it is
essentially an unorganized cluster of sheared 500mb vort maxima
tracking over the northern Great Lakes and Northeast. There will be
sufficient upper-level ascent thanks to the left-exit region of a
500mb jet streak will accompany the clipper. There is also
agreement on model guidance on healthy 850-700mb WAA via WSWrly
flow that collides with sufficiently cold boundary layer
temperatures over northern NY and the rest of northern New
England. However, guidance is not yet in agreement on where the
strongest 850-700mb FGEN takes shape, and as a result, disagree on
the placement of the QPF axis to the north of the storm track. WPC
Day 3 cluster analysis shows the departing trough over Nova Scotia
and the depth of the primary 500mb shortwave trough over the Upper
Midwest are the most sensitive factors in determining what this
clipper ultimately produces, and because of the notably shorter
wavelengths, confidence in where the heaviest snowfall will occur
is not clear out to Day 3.

So what we do know-- It is late March and elevation matters a ton.
However you slice it across deterministic guidance or
probabilistic guidance, the Adirondacks, Green, Whites, and
Berkshires are most favored for accumulating snowfall. Even as far
west as the MI U.P. and MN Arrowhead, snowfall totals approaching
4" are possible. WPC probabilities show low-to-moderate chances
(30-50%) for snowfall totals >4" in the Hurons of the MI U.P.
between Saturday night and through Sunday. Farther east, the

2,000ft elevations in the Adirondacks, Greens, and Whites sport

moderate chances (40-60%) for snowfall totals >8" on Sunday. Below
1,000ft, probabilities for snowfall amounts >4" are low (10-30%)
with most accumulations less than 4" expected at this time. WPC's
WSSI-P depicts moderate chances (40-60%) for Minor Impacts in the
MN Arrowhead to much of northern MI due to a combination of snow
and ice (WPC probabilities show low-to-moderate chances, or 30-50%,
for ice accumulations of at least one-hundreth of an inch) late
Saturday into early Sunday. Minor probabilities are highest in
northern New England where moderate probabilities (40-60%) are
present throughout the northern Appalachians. In fact, some
localized 40-50% probabilities for Moderate Impacts are shown
across south-central and Downeast Maine.


The chances for significant icing across the CONUS is less than 10
percent.


Mullinax




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FOUS11 KWBC 202018
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
418 PM EDT Fri Mar 20 2026

Valid 00Z Sat Mar 21 2026 - 00Z Tue Mar 24 2026

...Northeast...
Days 1-3...

A clipper will move into the Northeast Saturday night bringing a
swath of accumulating snowfall to Upstate NY into Northern New
England. Still some uncertainty with the exact track of this
system, which will impact where the heaviest swath of QPF is and
where the rain/snow line sets up. The higher elevations are most
favored for higher snowfall totals, but strong WAA should support a
period of moderate to locally heavy precipitation. This should
allow snow even down to the lower elevations of northern New
England, especially Saturday night into early Sunday. Snow ratios
from the NBM are likely too high with this system. While snow
should be coming down at a decent clip for a stretch, the strongest
lift appears to be mainly centered below the DGZ, which should cap
snowfall ratios. Then during the daylight hours the late March sun
will play a role in lowering ratios further. In fact, where snow
is falling at a lighter clip we probably won't see much
accumulation during the daytime, with accumulations focused in
either the highest terrain or where snow is falling at a heavy
enough clip to overcome the marginal temperatures and higher sun
angle.

The latest WPC snowfall probabilities have increased for the
Saturday night to Sunday timeframe. The probability of exceeding 4"
in the 24hr period ending 00z Monday are generally 40-80% from
Upstate NY into central to northern VT/NH and western ME. The
highest probabilities are in the higher terrain, but values of
30-50% even get into the lower elevation areas. The probabilities
of 6" are 30-60%, with 8" exceedance probabilities as high as
30-50% in the White Mountains of NH. These probabilities seem
reasonable, with exact snowfall totals dependent on the specific track
of the system. This is a scenario where the higher terrain has the
highest probabilities (and thus confidence) in seeing greater
snowfall totals, but there is still a lower risk of impactful snow
getting into some of the lower elevations if a snowfall band is
able to move into these areas overnight or early morning and is
heavy enough to overcome the marginal temperatures.

A bit more uncertainty exists on Monday as a coastal low tries to
develop offshore New England. By this time it will be cold enough
over northern New England for snow, but if precipitation intensity
is light then the high sun angle will likely limit accumulation.
However, a broader and/or more intense snow shield would be
capable of producing additional accumulating snowfall. Models have
been fluctuating regarding this low and inland precipitation
extent...although most 12z models shifted lighter with QPF. Even
the AIFS, which has been more consistently on the wetter side of
the QPF spectrum, did back off at 12z. There is still time for this
to change, but the probabilities of impactful snowfall Monday
appear to be decreasing, but still need to continue to monitor.

The chances for significant icing across the CONUS is less than 10
percent.


Chenard


$$

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FOUS11 KWBC 210715
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
315 AM EDT Sat Mar 21 2026

Valid 12Z Sat Mar 21 2026 - 12Z Tue Mar 24 2026

...Northeast...
Days 1-2...

A clipper system will move southeast out of central Canada and into
the Northeast this weekend. Snow on the leading edge of the
precipitation shield will move into upstate New York this evening,
then spread across New England tonight. The snow will be
characterized by warm advection. With a high sun angle and
plentiful warm air over much of the eastern half of the country,
the warm air will move into New York and southern New England,
resulting in a changeover to rain on Sunday over much of upstate
New York and into southern New England. Meanwhile, over most of
northern New England, the predominant precipitation type remains as
snow as the back edge of the precipitation quickly pushes east
across New England.

The southwesterly flow of warm air will be uplifted by the terrain
of the Adirondacks, Green, and White Mountains. Here, the
combination of upslope and cooler temperatures at higher
elevations will support multiple inches of snow. The heaviest snow
will fall between early Sunday morning and Sunday evening. In the
valleys, warmer temperatures, high sun angle, and snow mostly
falling during the day should all work to keep snow totals much
lower than the adjacent mountains, though still reaching into
advisory criteria. Where snow rates remain lighter, accumulations
during the day should be greatly tempered, and largely confined to
grassy areas.

WPC snowfall probabilities for the storm total snow over 4 inches
are high (over 70%) from the northern Adirondacks east across the
northern Greens of Vermont, northern Whites of New Hampshire, and
much of southern Maine. For much of northern New Hampshire and
western Maine, those probabilities are above 90% for 4 inches and
over 70% for 8 inches. As typical with compact storms, the exact
longevity and intensity of any internal heavy snow bands will
dictate where the highest snowfall totals are observed.

By D3/Monday, a secondary coastal low is expected to form south of
Long Island. The precipitation shield will be narrow and focus
across southern New England, where temperatures will be warm enough
for mostly (or entirely) rain. Thus, the chances for impactful
snow on Monday anywhere in the Northeast continue to decrease.

The chances for significant icing across the CONUS is less than 10
percent.


Wegman



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FOUS11 KWBC 211915
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
315 PM EDT Sat Mar 21 2026

Valid 00Z Sun Mar 22 2026 - 00Z Wed Mar 25 2026

...Northeast...
Days 1-2...

A clipper system will track across the Northeast late today through
Sunday with snow spreading into northern New York this evening and
northern New England overnight. While warm advection will be a
principle driver for the developing precipitation, it combined with
the high angle will support a changeover to rain across much of
Upstate New York and southern New England on Sunday. In contrast,
the higher elevations of the Adirondacks and much of northern New
England are expected to remain cold enough for snow to remain the
primary precipitation type before the system exits Sunday night.

Terrain-enchanced lifting along with cooler temperatures will
support heavier snow totals across portions of the Adirondacks,
Green, and White mountains -- with several inches likely, as
indicated by the greater than 50 percent WPC probabilities for
accumulations over 8 inches.

While lesser amounts are more likely across the lower elevations,
guidance indicates that low-to-mid level frontogenesis may help
contribute to banded heavier snowfall rates (0.5-1 in/hr) that may
be sufficient enough to support a swath of heavier totals from
east of the western Maine mountains to Down East Maine on Sunday.
Higher probabilities for amounts over 4 inches have expanded across
this area and are now greater than 70 percent across a broader
area. Additionally, probabilities for totals over 8 inches have
increased in this area also, with some greater than 50 percent
probabilities near the Maine coast.

Pereira

$$

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FOUS11 KWBC 220714
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
314 AM EDT Sun Mar 22 2026

Valid 12Z Sun Mar 22 2026 - 12Z Wed Mar 25 2026

...Northeast...
Days 1-2...

Snow has begun falling across the northern Appalachians and
northern New England this morning as 850-700mb WAA aloft overruns a
boundary layer sufficiently cold enough to support snow. Snowfall
rates around 1"/hr are likely over the Green and White Mountains
this morning, where the combination of heavy rates and elevation
will support accumulating snowfall. Given the snow is unfolding
during the day, and boundary layer temperatures are more marginal
in the valleys, snowfall will be tougher to accumulate but still
cause some minor accumulations in the Champlain Valley and along
coastal Maine today. Snowfall will gradually taper off by Sunday
evening with light snowfall over Downeast Maine still unfolding.
There will still be cases where light snow ensues over northern New
England Sunday night and into Monday morning as a strengthening
500mb trough approaches from the west and low-level easterly flow
directs some Atlantic moisture into the region. Additional light
snow accumulations of a coating to 3 inches are possible through
Monday.

48-hour WPC probabilities show high chances (>70%) for >4" of
snowfall throughout southern Maine, the White and Green Mountains,
and the peaks of the Adirondacks. In the Green and White Mountains,
elevations above 2,000ft are likely to see snowfall totals range
between 8-12", with some localized peaks (such as Mount Washington)
potentially receiving over a foot of snow. The WSSI primarily shows
Minor Impacts (winter driving conditions; use caution) with locally
some Moderate Impacts (hazardous travel conditions) possible,
particularly in passes and complex terrain.


...Washington Cascades & Olympics...
Day 3...

A Pacific storm system will direct a plume of moisture at the
Pacific Northwest Monday night and into Tuesday that leads to
higher elevation snowfall. Snow levels initially starting out
between 4,000-5,000ft Monday night and early Tuesday will drop to
as low as 2,500ft in the Olympics and 3,000ft in the northern WA
Cascades. WPC probabilities show moderate-to-high chances (50-80%)
for snowfall totals >4" above 3,000ft in the Olympics and above
4,000ft in the WA Cascades north of I-90. At this moment,
Snoqualmie and Stevens Passes show low chances (<20%) for
accumulating snowfall >4", but some minor accumulations late
Tuesday into Tuesday night are possible.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax




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FOUS11 KWBC 221931
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
331 PM EDT Sun Mar 22 2026

Valid 00Z Mon Mar 23 2026 - 00Z Thu Mar 26 2026

...Northern New England...
Day 1...

While the primary precipitation shield associated with a clipper
system crossing the Northeast is forecast to begin moving offshore
this evening, a secondary period of accumulating snow is expected
on Monday. An inverted trough, extending back from the departing
low, is forecast to develop and linger across eastern New England.
This feature will likely act to focus a north-south oriented band
of snow showers that could intensify late Monday as an
intensifying shortwave and associated cold pool aloft pivot into
the region from the west.

Given the added lift and some modest instability, localized heavier
bursts are possible, especially in northern New Hampshire and
western Maine where the inverted trough may align with favorable
upslope flow. WPC probabilities indicate that an additional 2-4
inches are possible with this band, with the highest probabilities
(50-70+ percent) focused over the northern New Hampshire and
western Maine mountains.

...Washington Cascades & Olympics...
Days 2-3...

A deepening storm lifting from the northeastern Pacific into
British Columbia will bring widespread moderate to heavy
precipitation into the region on Tuesday. However, the heaviest
precipitation rates are expected to coincide with relatively high
snow levels through Tuesday afternoon. Consequently, the bulk of
the significant accumulating snow (greater than 8 inches) will
remain above the major passes and confined to the higher peaks of
the Olympics and the northern Cascades.

As the front crosses the region late Tuesday and early Wednesday,
snow levels will begin to plunge toward 3,000 ft, but this cooling
will occur as the deepest moisture begins to shift east. However,
some of passes may see a period of rain changing to snow, impacting
travel.


The chances for significant ice across the CONUS is less than
10 percent.

Pereira

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FOUS11 KWBC 230726
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 AM EDT Mon Mar 23 2026

Valid 12Z Mon Mar 23 2026 - 12Z Thu Mar 26 2026

...Northern New England...
Day 1...

An inverted trough, extending back from the departing storm system
responsible for rounds of snow yesterday, will linger across
northern New England today. With sufficient low-level moisture off
the Atlantic and vertical ascent supplied by an approaching
shortwave trough to the west, periods of snow will continue over
the White Mountains. Some light snow is possible below 1,000ft, but
given the snow is occurring during daytime hours, snow will
struggle to accumulate on paved surfaces. WPC probabilities depict moderate-to-high chances (50-70%) for additional snowfall
accumulations >4" in the White Mountains, which included Mount
Washington. Otherwise, any additional snowfall accumulations below
2,000ft are likely to range between a coating-3".


...Washington Cascades & Olympics...
Days 1-3...

A strong and meandering closed upper low in the Gulf of Alaska will
direct a storm system forming on its southern flank at British
Columbia the first half of the week. With the Gulf of Alaska low
slow to move east and low level ridging in place off the southern
CA coast, low-level SWrly flow will supply a narrow corridor of
Pacific moisture into the Pacific Northwest Monday night and
through both Tuesday and into Wednesday. Snow levels will generally
reside above 3,000ft through Tuesday, but a cold frontal passage
and falling 700-500mb heights Tuesday night will cause snow levels
to dip to as low as 2,000ft by Wednesday. Still, the cold air in
wake of the cold frontal passage is not particularly cold, and the
best moisture advection will have already concluded by Wednesday.
This is likely to cause periods of mountain snow on Wednesday in
the Olympics and Cascades to as low as 2,000ft, but rates will not
be overly heavy even through Wednesday night.

WPC probabilities for >4" of snow are moderate-to-high (50-80%) for
elevations above 4,000ft north of I-90. Stevens Pass sports
moderate-to-high chances (50-80%) for snowfall totals >4" through
Wednesday night, while Snoqualmie Pass has moderate chances
(40-60%). Both passes sport low-to-moderate chances (20-40%) for
snowfall totals >8", so some locally hazardous travel conditions
are possible at pass level, but the heavier totals surpassing 8"
will likely be found at higher elevations for this event.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax




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FOUS11 KWBC 231844
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
244 PM EDT Mon Mar 23 2026

Valid 00Z Tue Mar 24 2026 - 00Z Fri Mar 27 2026

...Northern New England...
Day 1...

Latest surface analysis and RAP surface forecast indicate a defined
inverted trough axis bisecting NH up into neighboring Quebec with
some weak precipitation beginning to develop over far northern NH.
Expectation is for ascent to maximize within the trough axis later
this evening as flow focuses out of the north creating upslope flow
orthogonal to the terrain of the White Mountains leading to a
period of snowfall to develop as environmental conditions favor
frozen hydrometeors. Despite modest PWATs present over Northern New
England, the primary ascent pattern within the trough axis coupled
with upslope flow will generate localized moderate snowfall for
several hours creating a focal point of accumulating snow within
the White Mountains and some of the neighboring valleys. WPC
probabilities depict moderate- to- high chances (50-80%) for
additional snowfall accumulations >4" in the White Mountains, which
included Mount Washington. Otherwise, any additional snowfall
accumulations below 2,000ft are likely to range between a
coating-3".


...Washington Cascades & Olympics...
Days 1-3...

Little has changed from the previous forecast as the synoptic scale
pattern remains persistent within all guidance across the Pacific
Northwest. A strong and meandering closed upper low in the Gulf of
Alaska will direct a storm system forming on its southern flank at
British Columbia the first half of the week. With the Gulf of
Alaska low slow to move east and low level ridging in place off the
southern CA coast, low- level SWrly flow will supply a narrow
corridor of Pacific moisture into the Pacific Northwest later
tonight carrying through both Tuesday and Wednesday. Snow levels
will generally reside above 3,000ft through Tuesday, but a cold
frontal passage and falling 700-500mb heights Tuesday night will
cause snow levels to dip to as low as 2,000ft by Wednesday. Still,
the cold air in wake of the cold frontal passage is not
particularly cold, and the best moisture advection will have
already concluded by Wednesday. This is likely to cause periods of
mountain snow on Wednesday in the Olympics and Cascades to as low
as 2,000ft, but rates will not be overly heavy even through
Wednesday night.

WPC probabilities for >4" of snow are moderate-to-high (50-80%) for
elevations above 4,000ft north of I-90. Stevens Pass sports
moderate-to-high chances (50-90%) for snowfall totals >4" through
Wednesday night, while Snoqualmie Pass has moderate chances
(40-60%). Both passes sport low-to-moderate chances (20-50%) for
snowfall totals >8", so some locally hazardous travel conditions
are possible at pass level, but the heavier totals surpassing 8"
will likely be found at higher elevations for this event.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax/Kleebauer







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FOUS11 KWBC 240711
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
311 AM EDT Tue Mar 24 2026

Valid 12Z Tue Mar 24 2026 - 12Z Fri Mar 27 2026


...Washington Cascades & Olympics...
Days 1-2...

A strong and meandering closed upper low in the Gulf of Alaska
will direct a storm system forming on its southern flank at British
Columbia the first half of the week. With the Gulf of Alaska low
slow to move east and low level ridging in place off the southern
CA coast, low- level SWrly flow will supply a narrow corridor of
Pacific moisture into the Pacific Northwest today and into Wednesday.
Snow levels will generally reside above 3,000ft today, but a cold
frontal passage and falling 700-500mb heights Tuesday night will
cause snow levels to dip to as low as 2,000ft by Wednesday. Still,
the cold air in wake of the cold frontal passage is not
particularly cold, and the best moisture advection will have
already concluded by Wednesday. This is likely to cause periods of
mountain snow on Wednesday in the Olympics and Cascades to as low
as 2,000ft, but rates will not be overly heavy even through
Wednesday night.

WPC probabilities for >4" of snow are high (>70%) for elevations
above 4,000ft north of I-90. Stevens Pass sports high chances

70%) for snowfall totals >4" through Wednesday night, while

Snoqualmie Pass has moderate chances (50-70%). Stevens Pass poses
the slightly better odds for snowfall totals >8", ranging between
30-50%. Some locally hazardous travel conditions are possible at
pass level, but the heavier totals surpassing 8" will likely be
found at higher and more remote elevations.


...Northern Maine...
Days 2-3...

Starting Wednesday night, sheared lobes of 500mb vorticity racing
over the northern Great Lakes will generate PVA over northern New
England at the same time that low-level SWrly flow results in low-
level WAA and increased moisture content. Weak high pressure over
Quebec and sufficiently cold enough air over Maine will support
periods of snow over northern Maine with some minor icing possible
in central ME. As the first disturbance races east, a second 500mb
shortwave trough will spawn a second low over the northern Mid-
Atlantic Thursday evening. Periods of snow may envelope northern
Maine Thursday night as a cold front races south and forces
boundary layer temperatures to crash below freezing. There remains
some model spread in solutions regarding this second round of snow
Thursday night, so confidence in the snowfall placement and amounts
for the second round of snow is lower. At the moment, 48-hour WPC
probabilities show low chances (10-30%) for snowfall totals >4"
along the ME/Quebec border.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax





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FOUS11 KWBC 241849
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
249 PM EDT Tue Mar 24 2026

Valid 00Z Wed Mar 25 2026 - 00Z Sat Mar 28 2026


...Washington Cascades to Northern Rockies...
Days 1-2...

A shortwave trough rounding a deep, cold core low over the Gulf of
Alaska is directing an atmospheric river into the PacNW today with
high snow levels of 7000 to 8000ft. That trough axis approaches the
coast tonight before crossing the Cascades Wednesday and the
northern Rockies Wednesday night. Associated height falls drop the
snow level to 3500ft on the WA Cascades this evening before further
decreasing to around 2500ft Wednesday morning under the trough axis
(which is also when precip rates decrease). Snow probs for >6" are
40 to 80% above about 4000ft on the WA Cascades with some snow
getting down to 3500ft/Snoqualmie Pass level. Precip rates drop
off for the Cascades by Wednesday evening.

Farther inland, expect snow levels to decrease late tonight over
northwest MT and linger around 4000ft over northwest MT through
Wednesday. Day 1.5 snow probs for >6" are around 30% for the
highest Bitterroots and around 50% for the higher portions of the
Lewis Range in Glacier NP and the Mission Ridge which often stands
out for it's precip/snow forecast totals.


...Upper Midwest to Northern Maine...
Days 2-3...

Lee-side low development tonight in central Montana is expected
downstream of a trough axis approaching the Pacific Northwest. This
low tracks over Lake Superior Wednesday with snow generally in
Canada. However, it crosses Maine early Thursday producing moderate
snow over northern portions of the state. Day 2 snow probs for >4"
are limited to far northern NH terrain and only the higher points
of Maine.

A second and stronger wave crosses the northern Rockies Wednesday
night with an fgen band developing ahead over the northern Plains
early Thursday and shifts over the Northeast Thursday night. Some
snow mixed precip are likely with this band, though probabilities
are limited as of this time. The Day 2 ice probs for >0.01" are
40-70% from northern MN through the U.P. of MI.



Jackson


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FOUS11 KWBC 250707
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
307 AM EDT Wed Mar 25 2026

Valid 12Z Wed Mar 25 2026 - 12Z Sat Mar 28 2026

...Washington Cascades to Northern Rockies...
Days 1-2...

An approaching shortwave trough and an associated cold front will
track through the Pacific Northwest with upsloping winds and
sufficient Pacific moisture to produce mountain snow over the
Olympics and Cascades. Height falls and CAA in wake of a cold
frontal passage will cause snow levels to drop to as low as 2,500ft
this morning. Precipitation rates will gradually decrease
throughout the day, but persistent upslope flow will keep snow in
the forecast in the Cascades and Olympics as low as 2,500ft in
elevation through early Thursday morning. WPC probabilities depict
moderate chances (40-60%) for snowfall totals >4" at Snoqualmie
Pass and >8" at Stevens Pass. Most of the heaviest snowfall totals

8") will be confined to more remote elevations above 4,000ft.

Conditions at pass level should improve throughout the day Thursday
with snow concluding and higher late-March sun angles helping to
melt snow on paved surfaces.

Snow snow will spill east into the Northern Rockies as well, but
any accumulations will generally reside in the more remote
elevations (Glacier NPS the lone exception). Most snowfall amounts
will generally range between a coating to 3", but some locations
along the Lewis Range and Glacier NPS could see some localized
snowfall totals surpass 6" before snow concludes by Thursday
afternoon.


...Upper Midwest to Northern Maine...
Days 2-3...

A series of sheared 500mb vort maxima will generate light wintry
precipitation in portions of the Upper Midwest and northern Maine
the second half of the week. Focusing on northern Maine first, a
clipper system racing through southeast Canada Wednesday night will
escort a plume of moisture aloft within a corridor of 850-700mb
WAA over New England. Most of New England's boundary layer
temperatures will be too mild to support snow, with the lone
exception being far northern Maine. Snow will develop over northern
Maine late Wednesday night and linger through Thursday morning,
before finally ending Thursday afternoon. Snow fall rates will not
be overly heavy and the bulk of the snowfall will occur during the
day, which will limit snowfall totals thanks to the increasing
strength of the late March sun angle. Still, the border of Quebec
and northern Maine could still pick up some localized snowfall
totals >4" (WPC 24-hour probabilities show low-to-moderate chances
(20-40%). Some light snow may linger into Friday over the northern
Appalachians and northern Maine Friday morning as the next clipper
system passes well to the south.

At the same time as snow is unfolding across northern Maine on
Thursday morning, the next 500mb vort max is racing through the
Upper Midwest with a weak surface low tracking from eastern NE
into the heart of the MS Valley. Minor freezing rain and snow
accumulations will occur on the northern flank of the storm track
with WPC probabilities showing moderate-to-high chances (50-80%)
for >0.01" of ice accumulation from as far west as eastern ND to as
far east of the tip of Michigan's Mitt. It is worth noting WPC
probabilities for >0.1" of ice are <10%, so most ice accumulations
will be minor and struggle to accumulate on paved surfaces,
especially during the day on Thursday. The Huron Mountains are the
lone area where localized snowfall totals could top 2", but
otherwise the marginal boundary layer temperatures will make
snowfall more conversational rather than impactful on Thursday
morning.


The chances for significant icing across the CONUS is less than
10%.


Mullinax




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FOUS11 KWBC 251802
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
202 PM EDT Wed Mar 25 2026

Valid 00Z Thu Mar 26 2026 - 00Z Sun Mar 29 2026

...Washington Cascades to Northern Rockies...
Day 1...

Shortwave trough and associated cold front crosses the Cascades by
this evening with snow rates declining as snow levels fall from
3000ft to 1000ft. Day 1 snow probs for >4" are generally 30-60%
above about 3500ft.

Additional snow shifts east tonight through Thursday over the
Lewis Range in Glacier NP, the Bitterroots, Red Lodge portion of
the northern Absarokas in MT and the Bighorns. Day 1 snow probs are
30-50% across these areas of terrain.


...Northern Maine...
Day 1...

Weak low pressure over northern MI this afternoon strengthens as it
shifts across Maine on Thursday. WAA ahead of the low brings snow
to Maine late tonight/Thursday morning. Day 1 snow probs for >4"
are limited to far northern NH and the highest elevations and
northern border of Maine and generally 20-40%.


...Northern Plains and Upper Midwest...
Days 1 and 3...

A tight baroclinic zone develops tonight in zonal flow as low
pressure over the central Plains is met by strong high pressure
shifting from the Canadian Prairies. A wintry mix with generally
light rates develops along this boundary. Day 1 ice probs for

0.01" ice are 30-60% over eastern ND and across northern WI to

Upper MI, mainly falling late tonight through Thursday morning.
Little snow accum is expected.

High pressure shifting from the northern Plains to the Midwest
Friday through Saturday promotes some LES to develop off Lake
Superior on NW flow. Day 3 snow probs for >4" are 30-50% over the
eastern U.P.


The chances for significant icing across the CONUS is less than
10%.


Jackson



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FOUS11 KWBC 260716
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
316 AM EDT Thu Mar 26 2026

Valid 12Z Thu Mar 26 2026 - 12Z Sun Mar 29 2026

...Northern New England...
Day 1...

A weak area of low pressure and a trailing front will bring some
light snow to northern New England. Amounts will be light and
generally limited to the higher elevations due to marginal
temperatures. WPC probabilities for at least 4 inches of snow are
low, generally 10-20%, above 2000-3000ft or so.


...Upper Midwest and western Great Lakes...
Days 1-3...

A frontal boundary across the region has prompted some light icing
overnight that will continue this morning after 12Z, particularly
over northeastern WI, southern U.P. of Michigan, and into northern
Lower Michigan. WPC probabilities for at least 0.01" icing are
moderate (40-70%) in these regions, but are below 5% for amounts
higher than a tenth of an inch.

Colder air behind this system will move across the Great Lakes
Friday afternoon into Saturday, coincident with a mid-level
shortwave. With 850mb temperatures dipping to below -15C, some lake enhanced/effect snow is forecast for parts of the U.P. into
northern Wisconsin. Another weak shortwave Saturday evening will
bring another light dusting to an inch of snow to the U.P. of
Michigan. Amounts even across all three days should be light (1-2"
or so), and WPC probabilities for at least 4 inches are only 10-20%
for the period.



The probability of significant icing across the CONUS for days 1-3
is less than 10%.


Fracasso

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FOUS11 KWBC 261933
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
333 PM EDT Thu Mar 26 2026

Valid 00Z Fri Mar 27 2026 - 00Z Mon Mar 30 2026

...Northern New England...
Day 1...

Low pressure lifting from northern New England into southeastern
Canada, along with a trailing front, will bring some light snow to
northern New England. Amounts will be light and generally limited
to the higher elevations due to marginal temperatures. WPC
probabilities for at least 4 inches of snow are low - capped at
10-20 percent and confined mostly to the far northern Green and
White mountains.

...Upper Midwest Great Lakes...
Days 2-3...

Cold air will continue to spread across the region as a mid-level
shortwave drops into the region by late Friday. With 850mb
temperatures dipping to below -15C, some lake enhanced/effect snow
is forecast for parts of region, with mostly light amounts
expected from northern Michigan to Upstate NY. Another weak
shortwave Saturday evening will bring another light dusting to an
inch of snow to the U.P. of Michigan. WPC probabilities indicate
that three-day snow accumulations will likely only be an inch or
two at most across the region.


The probability of significant icing across the CONUS for days 1-3
is less than 10%.


Pereira


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FOUS11 KWBC 270707
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
307 AM EDT Fri Mar 27 2026

Valid 12Z Fri Mar 27 2026 - 12Z Mon Mar 30 2026

...Western Great Lakes...
Day 1...

Cold air (850mb temperatures around -15C) over the western Great
Lakes will support light snow across the region tonight as a mid-
level shortwave moves through the region this afternoon/tonight.
Amounts will be light (1-2") but could touch 4" over parts of the
U.P. of Michigan where WPC probabilities are near 10%.


...Pacific Northwest/Northern Rockies...
Day 3...

Upper trough diving southeastward along the BC coast will move
into the Pacific Northwest on Sunday, bringing some mountain snow
to the Cascades and then into the northern Rockies along the
Divide. Colder air will rush in behind the cold front, allowing
snow levels initially near 2500-4000ft to fall to 1500-3000ft
overnight Sunday into early Monday (Cascades) but remain around
5000-600ft over northwestern MT. This will get some light snow to
the passes in WA, but probabilities for at least 4 inches of snow
are greater than 50% above about 4000-5000ft (Cascades) and 6000ft
over the Lewis Range.


The probability of significant icing across the CONUS for days 1-3
is less than 10%.

Fracasso

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FOUS11 KWBC 271900
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Fri Mar 27 2026

Valid 00Z Sat Mar 28 2026 - 00Z Tue Mar 31 2026

...Pacific Northwest/Northern Rockies...
Day 3...

Guidance maintains general run-to-run continuity for the next
disturbance to impact the Northwestern U.S. by the end of the
weekend. Upper trough diving southeastward along the BC coast will
move into the Pacific Northwest on Sunday, bringing some mountain
snow to the northern Cascades and then into the northern Rockies
along the Divide. Colder air will rush in behind the cold front,
allowing snow levels initially near 2500-4000ft to fall to
1500-3000ft overnight Sunday into early Monday (Cascades) but
remain around 5000-600ft over northwestern MT. This will get some
light snow to the passes in WA, but probabilities for at least 4
inches of snow are greater than 50% above about 4000-5000ft
(Cascades) and 6000ft over the Lewis Range.


The probability of significant icing across the CONUS for days 1-3
is less than 10%.

Fracasso/Kleebauer




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FOUS11 KWBC 280647
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
247 AM EDT Sat Mar 28 2026

Valid 12Z Sat Mar 28 2026 - 12Z Tue Mar 31 2026

...Pacific Northwest/Northern Rockies...
Days 2-3...

A closed low south of the Gulf of Alaska will continue
southeastward today and slowly weaken into a positively-tilted
upper trough as its cold front moves through WA/OR on Sunday.
Despite some injection of mid-latitude Pacific moisture, the system
will be progressive and QPF will be limited. Snow levels will be
on the lower side -- 2500-4000ft in the Cascades before lowering
further behind the front to 1500-3000ft. This will bring some snow
to the passes and probabilities for at least 6 inches are at least
50% above about 3000ft or so for the northern Cascades.

Farther east, moisture will stream into the northern Rockies and
eventually into northern/northwestern Wyoming Sunday evening
through Monday and overnight into very early Tuesday, ending from west/northwest to east/southeast. Amounts will again be generally
light, with probabilities of at least 6 inches at least 50% above
about 5000ft in ID/MT but above 9000-10,000ft in WY.

Front end of the precip shield advancing across the Northern
Plains could support some light icing over northern ND early Monday
with generally a few hundredths of an inch possible.


The probability of significant icing across the CONUS for days 1-3
is less than 10%.

Fracasso


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FOUS11 KWBC 281903
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
303 PM EDT Sat Mar 28 2026

Valid 00Z Sun Mar 29 2026 - 00Z Wed Apr 01 2026

...Pacific Northwest/Northern Rockies...
Days 2-3...

A closed low south of the Gulf of Alaska continues to trek to the
southeast as evidenced by the latest WV satellite analysis.
Expectation is for the low to slowly weaken into a positively-
tilted upper trough as its cold front moves through WA/OR on
Sunday. Despite some injection of mid- latitude Pacific moisture,
the system will be progressive and QPF will be limited. Snow levels
will be on the lower side -- 2500-4000ft in the Cascades before
lowering further behind the front to 1500-3000ft. This will bring
some snow to the passes and probabilities for at least 6 inches are
at least 50% above about 3000ft or so for the northern Cascades.

Farther east, moisture will stream into the northern Rockies and
eventually into northern/northwestern Wyoming Sunday evening
through Monday and overnight into very early Tuesday, ending from west/northwest to east/southeast. Amounts will again be generally
light, with probabilities of at least 6 inches at least 50% above
about 5000ft in ID/MT but above 9000-10,000ft in WY. Highest totals

8" are most likely across the Lewis Range in northwest MT and the

Absoroka's in southern MT into northwest WY with the Lewis Range's
likely to see a foot or more above 7000ft.

Front end of the precip shield advancing across the Northern
Plains could support some light icing over northern ND early Monday
with generally a few hundredths of an inch possible.

The probability of significant icing across the CONUS for days 1-3
is less than 10%.

Fracasso/Kleebauer





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FOUS11 KWBC 291906
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
306 PM EDT Sun Mar 29 2026

Valid 00Z Mon Mar 30 2026 - 00Z Thu Apr 02 2026

...Pacific Northwest/Northern Rockies...
Days 1-2...

Trough axis from this morning over British Columbia will continue
to propagate to the east over the next 12+ hours. A cold front
analyzed just off the coast of WA is making headway into the
northwestern fringes of the state which will lead to a decay of
precipitation from west to east, post front. Snowfall will continue
across the highest elevations of the Olympics, as well as over the
northern Cascades through this evening before precipitation wanes
overnight into the early morning hours tomorrow. Additional light
to moderate snowfall accumulations are anticipated through the
aforementioned time frame before conditions settle and snowfall
potential ceases.

Farther east, moisture will continue to stream into the northern
Rockies through tonight and eventually into Wyoming late Monday
into Tuesday, ending from west/northwest to east/southeast as the
cold front moves to the east quicker than it sinks to the south.
Snowfall totals across the Lewis Range will likely exceed a foot
for the entirety of the event before the precipitation shield
shifts south in wake of the front. Additional accumulations >6" are
running between 50-80% above 7000ft from now until late Monday
afternoon. Snowfall levels will settle closer to 8000-10,000ft in
WY leading to lighter accumulations overall with the setup. The
Absarokas in southern MT into northwest WY are the exception where
slightly higher totals are forecast due to some local surface
convergence and terrain enhancement along and ahead of the cold
front.

Front end of the precip shield advancing across the Northern
Plains could support some light icing (generally a few hundredths
of an inch) over northern ND early Monday then into northeastern MN
and perhaps the U.P. of Michigan as the system redevelops over the
Plains/Corn Belt.

...Northern New England...
Day 3...

The system over the Great Lakes on Monday (above) will move into
the Northeast on Tuesday. Marginally cold temperatures will be
limited to northern NY/VT/NH and much of interior Maine as
precipitation advances into the region Tuesday morning along and
ahead of a surface warm front. With the main area of low pressure
quite far to the west early Tuesday (WI or into Lower MI), cold air
may hang on longer in sheltered areas over northern New England
which would support some light snow to start but then more likely a
period of freezing rain will materialize as southwesterly flow
aloft advects in some warmer air within the upper portion of the
boundary layer into the mid-levels. Latest WPC probabilities for

0.1" of ice accumulation are upwards of 20-40% for the D3 period,

majority of which will fall in the evening to overnight hours
Tuesday into Wednesday morning. A low-end chance for up to a 0.25"
is hovering between 5-15% within an axis aligned west to east
across northwest ME through much of Aroostook county and the
northern sections of neighboring Piscataquis/Penobscot counties.
Will monitor trends closely, but mainly expecting modest totals
with generally a 0.05-0.15" range for the forecast.


...Sierra Nevada to the CO Rockies...
Day 3...

Combination of the tail-end of the Pacific Northwest/northern
Rockies system today/Monday and an incoming weak shortwave out of
the Pacific Tuesday afternoon will bring some light to perhaps
modest snow to the Sierra and CO Rockies and dotted across the
Great Basin in between. Snow levels will be high -- 8000-9000ft --
with WPC probabilities for at least 6 inches of snow between about
40-80% above 9000-10,000ft. Heavier snowfall into the Central
Rockies will occur just after the D3 window (D3.5) where
probabilities are closer to 50-80% for at least 6" when advancing
just beyond the D3 window.

Fracasso/Kleebauer






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FOUS11 KWBC 300742
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Mon Mar 30 2026

Valid 12Z Mon Mar 30 2026 - 12Z Thu Apr 02 2026

...Northern Rockies...
Day 1...

Cold front moving eastward through the Northern Rockies will
continue to bring generally light snow to the central ID ranges
into the Absarokas and Bighorns today. The snow associated with
this system will be supplanted by incoming moisture from a Pacific
system. Through 12Z Tue, WPC probabilities of an additional 6
inches of snow are >50% over the Absarokas.


...Sierra Nevada to the CO Rockies...
Days 2-3...

An incoming shortwave out of the Pacific Tuesday afternoon will
bring some light to perhaps modest snow to the Sierra, Wasatch,
Uintas, and CO Rockies as it zips eastward. Snow levels will be
high (8000-9000ft though falling ~1000ft as the trough moves
through) with WPC probabilities for at least 8 inches of snow are
at least 50% above 7500ft (Sierra) to 10,000ft (CO). Totals in the
CO Rockies may eclipses a foot above 11,000ft.


...Pacific Northwest...
Day 3...

Next system out of the Gulf of Alaska will barrel toward the
Pacific Northwest on Wednesday, bringing a more substantial influx
of moisture ahead of its rather robust cold front. Trailing mid-
level low will sustain modest snowfall totals into the Cascades and
points eastward to the northern Rockies yet again. The focus may
be the southern WA Cascades, OR Cascades, central ID ranges, and
NorCal ranges including the northern Sierra as the cold front
reaches there by the end of this forecast period. Snow levels will
range from 4000-7000ft (north to south) ahead of the front, then
fall to 2500-6000ft post-FROPA. WPC probabilities for at least 8
inches of snow are >50% above 5000ft or so in the OR Cascades and
7000ft in NorCal and across the northern Great Basin.


...Northern New England...
Day 2...

The system exiting the High Plains today will move into the
Northeast on Tuesday. Marginally cold temperatures will be limited
to northern NY/VT/NH and much of interior Maine as precipitation
advances into the region Tuesday morning along and ahead of a
surface warm front. With the main area of low pressure quite far to
the west early Tuesday (WI or into Lower MI), cold air may hang on
longer in sheltered areas over northern New England which would
support some light snow to start but then more likely a period of
freezing rain will materialize as southwesterly flow aloft advects
in some warmer air within the upper portion of the boundary layer
into the mid-levels. With the surface low track potentially no
farther north than the VT-NH/Quebec border, this could prolong the
freezing rain threat for much of the event. WPC probabilities for

0.25" of ice accumulation are 10-30% across northwest ME.

...Upper Midwest/Corn Belt/Western Great Lakes...
Day 3...

System exiting the Rockies Wednesday will lift to the northeast
toward the Great Lakes. With a generous fetch of moisture from the
Gulf northward and a marginally but sufficiently cold thermal
profile north of about I-80, an expanding area of
snow/sleet/freezing rain is increasingly likely for much of the
region overnight Wednesday through Thursday (continuing beyond this
forecast period). Uncertainty is high, compounded by the spread in
ptypes from the models/ensembles. For now, through 12Z Thursday,
expect a west-to-east swath of snow farthest to the north (SD
eastward to WI and MI) and sleet/freezing rain just to the south
(Iowa eastward through southern WI into Lower MI). Again, these
areas may shift over the next couple of days depending on how the
storm evolves over/east of the Rockies. Just through 12Z Thursday,
WPC probabilities for at least 4 inches of snow are 10-40% from SD
eastward to about northern WI. For freezing rain, probabilities for
at least 0.10" icing through 12Z Thursday are 10-50% over southern
WI and into central Lower MI. The probabilistic WSSI is already
showing 20-40% chance of moderate impacts day 3, and even higher
beyond. See our extended forecast discussion (PMDEPD) for more
information.



Fracasso

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FOUS11 KWBC 301900
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Mon Mar 30 2026

Valid 00Z Tue Mar 31 2026 - 00Z Fri Apr 03 2026

...Northern Rockies...
Days 1-3...

A cold front pushing south and east through the northern Rockies
today will work together with an influx of 700-300mb layer moisture
and the diffluent right-entrance region of a 250mb jet streak to
produce snow from the Bitterroots on east through the Absaroka,
Wind River, Teton, and Big Horn Ranges tonight and into Tuesday.
Snow ill linger through Tuesday due to weak upslope easterly flow
from high pressure over southern Saskatchewan and and moist SWrly
700mb winds maintaining a steady fetch of Pacific moisture.
Snowfall rates will generally be on the light side on Tuesday with
weakening synoptic-scale lift aloft. Through 00Z Wednesday, WPC
probabilities depict moderate-to-high chances (50-80%) for snowfall
totals >4" in the Absaroka, Tetons, Wind River, and Big Horn
ranges. The peaks of the MT/WY Absaroka and the Wind River
mountains may witness some localized snowfall totals approaching a
foot.

Periods of light mountain snow will continue through Tuesday night
and Wednesday morning before the next round of heavier mount snow
arrives Wednesday night. The 500mb low responsible for the heavy
mountain snow in the Pacific NW will direct its rich plume of
Pacific moisture into the Northern Rockies. At the same time, its
diffluent 250mb left-exit quadrant will be in place over the
region at the same time healthy 500mb PVA occurs. There is no
frigid air-mass in advance of this system, keeping most heavy
snowfall above 4,000ft from the Bitterroots and Sawtooth on east to
the Lewis Range. For the Absaroka, Tetons, and as far east as the
Big Horns, heavier snowfall totals will be at/above 7,000ft. WPC
probabilities highlight at least moderate chances (>50%) for
snowfall totals >6" in the peaks of all these aforementioned ranges
with localized totals up to a foot possible. The WSSI-P shows that
there are high chances (>70%) for Minor Impacts in the peaks and
passes of these regions, but Moderate Impact probabilities remain
on the low side (<20%). This indicates some hazardous travel is
possible, although more significant impacts are not anticipated at
this time.

Many of these mountains regions are either right around normal, or
below normal for the season-to-date snowfall, so snowfall in the
northern Rockies will be more beneficial than harmful as we
approach the start of the warm season.


...Pacific Northwest...
Days 2-3...

A powerful closed upper-low diving southward from the Gulf of
Alaska will be the catalyst for renewed mountain snow in the
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far
east as the Blue Mountains Wednesday afternoon and continuing
through Thursday. The approaching 850-500mb layer heights
associated with the closed low are below the 10th percentile and
snow levels will be able to drop as low as 2,000ft Wednesday night
in the Olympics, Cascades, and even as far south as the Siskiyou.
A steady stream of Pacific moisture embedded within SWrly mean
layer flow, suitable for upslope enhancement as well, will also
favor locally heavy snowfall rates in these ranges. Drier air
should move in on the backside of the closer low by Thursday
afternoon, although lingering westerly low-level winds should
support light-to-moderate snow in the Cascades for the remainder of
the day on Thursday.

WPC 48-hour probabilities show high chances (>70%) for snowfall
totals >12" in the OR Cascades above 4,000ft with at least
moderate chances (>50%) for snowfall totals >8" at elevations

3,000ft. The WA Cascades will see lesser snowfall totals than

their OR neighbors given the best Pacific moisture plume will
reside farther south, but several inches of snow at pass level
(Snoqualmie and Stevens) are expected. The peaks of the Siskiyou
and Salmon Mountains of northern CA, as well as the peaks of the
Blue Mountains of northeast OR, all have high chances (>70%) for
snowfall totals surpassing 8". Most impacts on the WSSI currently
show Minor Impacts with locally Moderate Impacts depicted in the
peaks of these mountain ranges through Thursday.


...Sierra Nevada to the Colorado Rockies...
Days 2-3...

An incoming shortwave out of the Pacific Tuesday afternoon will
bring some light to perhaps modest snow to the Sierra Nevada,
Wasatch, Uintas, and CO Rockies as it zips eastward. Snow levels
will be high (8000-9000ft though falling ~1000ft as the trough
moves through) with WPC probabilities for at least 8 inches of snow
are at least 50% above 7500ft (Sierra) to 10,000ft (CO). Totals in
the CO Rockies may eclipses a foot above 11,000ft.


...Northern New York and New England...
Days 1-3...

A lingering front will become the focus for organized
precipitation as a series of low-amplitude southern stream waves
interact with deepening moisture. Light precipitation will spread
across the region on Tuesday with the first wave, followed by
heavier precipitation Tuesday night as a following wave
strengthens ahead of a more amplified northern stream wave moving
across Quebec. While southwesterly flow aloft advects warmer air
into the mid-levels, a shallow but stubborn layer of subfreezing
air is expected to remain entrenched across northern New England.
Forecast soundings support mostly snow across far northern Maine,
while areas further south, including areas as far south as Down
East Maine may see snow transitioning to accumulating ice. The
latest guidance indicates that northwestern Maine is the area
mostly likely to be impacted with heavier ice accumulations, with
WPC probabilities showing 30-50 probabilities for ice accumulations
of 0.10 inch or more centered across the region 00Z Wednesday -
00Z Thursday. Northern Aroostook County is likely to be the focus
for the heaviest snow accumulations, with WPC probabilities
indicating that amounts greater than 4 inches are likely (50-70
percent).

Following a brief dry period Wednesday night, the threat for
wintry weather is forecast to return to the region on Thursday as
the system detailed below lifts toward the Great Lakes -- bringing
moisture back into the region as cold high pressure remains
anchored to the north. For the 24-hr period ending 00Z Friday, WPC probabilities indicate that additional accumulating ice is likely
for parts of the Adirondacks, with lower probabilities extending
east to Down East Maine.

...Upper Midwest/Corn Belt/Western Great Lakes...
Day 3...

An amplified shortwave exiting the Rockies Wednesday night will
lift toward the Great Lakes, directing a deep plume of Gulf
moisture to the north. As precipitation blossoms across the region
on Thursday, a sharp thermal gradient north of the I-80 corridor
will support a broad swath of wintry weather, topped by west-east
band of heavy snow and bordered to the south by a corridor of
sleet and freezing rain, with significant ice accumulations
possible.

Through 00Z Friday, WPC probabilities greater than 50 percent for
snow accumulations greater than 4 inches are largely confined to
the Minnesota Arrowhead eastward to the western U.P.

At this point, guidance indicates that significant icing will be a
more far-reachiing concern. By 00Z Friday, the P-WSSI shows
probabilities greater than 50 percent for moderate impacts due to
icing continuing to expand across the region, now covering parts
of southeastern Minnesota and northeastern Iowa, as well as large
potions of central and southern Wisconsin, and northern and central
Lower Michigan. For the 24-hr period ending 00Z Friday, WPC
probabilities for ice accumulations greater than 0.10 inch are
50-70+ percent across this area, with the higher probabilities
generally corresponding with 30-50 probabilities for ice
accumulations greater than 0.25 inch.

Mullinax/Pereira/Fracasso


$$

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FOUS11 KWBC 310749
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
349 AM EDT Tue Mar 31 2026

Valid 12Z Tue Mar 31 2026 - 12Z Fri Apr 03 2026

...Potentially impactful mixed precipitation event increasingly
likely for the Upper Midwest into the Great Lakes Thursday...


...Sierra Nevada to the Rockies...
Days 1-2...

An incoming shortwave out of the Pacific this afternoon will bring
some light to perhaps modest snow to the Sierra Nevada, Wasatch,
Uintas, and CO Rockies as it zips eastward. To the north, lingering
moisture along a stationary surface boundary will maintain light
snow over the ID ranges into Wyoming with additional accumulation.
Snow levels will be high (8000-9000ft to the south, though falling
~1000ft as the trough moves through) with WPC probabilities for at
least 8 inches of snow are at least 50% above 7500ft (Sierra) to
10,000ft (CO). Totals in the CO Rockies may eclipses a foot above
11,000ft. Over ID into WY, WPC probabilities for at least 8 inches
of snow are at least 50% above 8000ft.


...Pacific Northwest to the Northern Rockies...
Days 2-3...

A powerful closed upper-low diving southward from the Gulf of
Alaska will be the catalyst for renewed mountain snow in the
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far
east as the Blue Mountains Wednesday afternoon and continuing
through Thursday. The approaching 850-500mb layer heights
associated with the closed low are below the 10th percentile and
snow levels will be able to drop as low as 2,000ft Wednesday night
in the Olympics, Cascades, and even as far south as the Siskiyou. A
steady stream of Pacific moisture embedded within SWrly mean layer
flow, suitable for upslope enhancement as well, will also favor
locally heavy snowfall rates in these ranges. Drier air should move
in on the backside of the closed low by Thursday afternoon,
although lingering westerly low-level winds should support light-
to-moderate snow in the Cascades for the remainder of the day on
Thursday with all precipitation ending by early Friday morning west
of the Divide.

To the east, snow will start overnight tomorrow night and continue
through this forecast period (12Z Fri) over Montana. With a closed
low track from the WA/OR border ESE across central ID into central
WY, snow will maximize over the Blue Mountains, Bitterroots,
Absarokas, Tetons and into the Bighorns. The western MT ranges will
also see moderate snow totals closer to the 700mb low and old
triple point surface low.

WPC 48-hour probabilities for at least 12 inches of snow are high

70%) in the OR Cascades above 4,000ft with at least moderate

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,
but several inches of snow at pass level (Snoqualmie and Stevens)
are expected. To the east, WPC probabilities for at least 12 inches
of snow are at least 50% above 7000ft or so.


...Northern New York and New England...
Days 1&3...

A lingering front will become the focus for organized
precipitation as a series of low-amplitude southern stream waves
interact with deepening moisture. Light precipitation will spread
across the region today with the first wave, followed by heavier
precipitation tonight as a following wave strengthens ahead of a
more amplified northern stream wave moving across Quebec. While
southwesterly flow aloft advects warmer air into the mid-levels, a
shallow but stubborn layer of sub-freezing air is expected to
remain entrenched across northern New England. Forecast soundings
support mostly snow across far northern Maine, while areas farther
south, including areas as far south as Downeast Maine, may see snow transitioning to accumulating ice. Guidance continues to indicate
that northwestern Maine is the area mostly likely to be impacted
with heavier ice accumulations. WPC probabilities of at least a
tenth of an inch of ice are 30-50% over the Central Highlands and
northern White Mountains. Northern Aroostook County has the highest
chance of staying all snow, with WPC probabilities of at least 4
inches 50-90%.

Following a brief dry period Wednesday night, the threat for
wintry weather is forecast to return to the region on Thursday as
the system detailed below lifts toward the Great Lakes -- bringing
moisture back into the region as cold high pressure remains
anchored to the north. For Day 3, the setup again would favor all
snow over far northern Maine then quickly transitioning to sleet
and freezing rain for the Central Highlands southwestward through
much of northern NH, the Northeast Kingdom of Vermont, and the
northern Adirondacks. WPC probabilities for at least 4 inches of
snow are 30-50% along the northern Maine border with Canada (North
Woods area). For freezing rain, WPC probabilities for at least a
tenth of an inch of ice are at least 30% over the northern CT River Valley/Northeast Kingdom into central/northern NH and northwestern
Maine.


...Upper Midwest/Corn Belt/Western Great Lakes...
Days 2-3...

An amplified shortwave exiting the Rockies Wednesday night will
lift toward the Great Lakes, directing a deep plume of Gulf
moisture to the north. As precipitation blossoms across the region
on Thursday, a sharp thermal gradient north of the I-80 corridor
will support a broad swath of wintry weather, topped by a west-
east band of heavy snow and bordered to the south by a corridor of
sleet and freezing rain, with significant ice accumulations
possible. Uncertainty remains high overall due to a shifting storm
track in the models (northwest trend since yesterday) and ptype
uncertainty through the storm evolution as many areas will see a
transition from snow or sleet to freezing rain and perhaps just
rain. Though precipitation may be still ongoing at the end of this
forecast period (12Z Fri), the heaviest will likely be on Thursday.

Through 12Z Friday, WPC probabilities for at least 4 inches of
snow are at least 50 percent from portions of the eastern Dakotas
through much of central to northeastern MN (especially the
Arrowhead), northern WI, and into the western U.P. of Michigan. The
highest probabilities of snowfall in excess of 8 inches lies over
the Arrowhead (30-60% chance).

The freezing rain may be significant within a broad region that
may see at least some icing; namely, SD through MN and WI to MI.
WPC probabilities for at least a tenth of an inch of ice are at
least 30% over much of Wisconsin into the U.P. and the northern 1/3
of Lower Michigan. Some areas could see in excess of 0.25" icing,
specifically central WI and northern Lower Michigan, but this is
subject to change with the storm track. The probability of Moderate
impacts per the WSSI-P are at least 40% in these areas.


Fracasso/Mullinax/Pereira



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FOUS11 KWBC 311925
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
325 PM EDT Tue Mar 31 2026

Valid 00Z Wed Apr 01 2026 - 00Z Sat Apr 04 2026


...Northern Plains through the Great Lakes...
Days 1-3...

...Significant late season snow and freezing rain likely to create
substantial impacts through mid-week...

Late season winter storm will begin on Wednesday as a lee side low
pressure system develops across eastern Colorado. This low will
develop in response to a shortwave which will emerge from the
Pacific over California and then sharpen as it moves across the
Four Corners Wednesday. This shortwave is expected to then develop
a negative tilt as it pushes into the Upper Midwest Thursday before
exiting into Canada by Friday morning. The combination of
impressive downstream divergence ahead of this sharpening
shortwave, followed by height falls and the LFQ of a modest but
strengthening meridionally arcing jet streak will provide
widespread deep layer ascent to help deepen the surface low as it
tracks from Colorado northeast into Michigan.

The challenge for this period primarily revolves around the track
and timing of this low, as there is high confidence in its
development. Over the past 4 cycles of the ECENS and GEFS, the
surface low clusters have become more consolidated, but continue to
feature a subtle N/NW trend. This is in response to a small
deepening trend in the upper pattern, although the EC-AIFS has been exceptionally consistent with its track, so while the NW trend may
continue, it appears that is slowing and beginning to consolidate
leading to higher confidence overall.

As this low develops and tracks northeast, impressive moisture will
spread northward to support a large swath of all p-types. An
impressive IVT plume (>90% for 250 kg/m/s pushing well into the
Rockies) will support upper level moisture into the system, while
low-level moisture fueled by increasing WAA out of the Gulf help to
saturate the low-levels. The accompanying theta-e ridge emerging
northward will help expand the precipitation shield thanks to PW
anomalies that surge above the 99th percentile according to NAEFS.
This will result in periods of heavy precipitation, first across
the Dakotas Wednesday morning and then expanding eastward within
the WAA plume, reaching Michigan by Thursday morning, with
precipitation continuing through Thursday night, potentially
Friday morning across northern MN, before ending across the area.

In the locations that receive mostly snow, which is expected to be
the Dakotas, and the northern half of Minnesota, heavy
accumulations appear likely. In this area, snowfall rates of 1"/hr
appear likely through both WAA and then deformation on the NW side
of the low as it deepens, leading to 48-hr WPC probabilities that
are moderate (50-70%) for at least 4 inches of snow, with locally
more than 8 inches possible (10-30%) from the Buffalo Ridge through
the Arrowhead of MN and the western U.P. of MI. Lighter snowfall of
2-4" is likely south/east of this axis including the northern
suburbs of the Twin-Cities and Green Bay, where heavy snow will
develop but rapidly changeover to a mix and then rain, leading to
lesser snowfall.

The most substantial impacts from this event may be due to freezing
rain rather than ice. Although the Canadian high pressure over
Ontario will retreat quickly, antecedent wet-bulb temperatures are
well below freezing (in the low to mid 20s) due to very dry
dew point temperatures. Although these will slowly warm as the
impressive warm nose surges northward, there is likely to be an
extended period of freezing rain (after a period of snow and sleet)
from the IA/MN border northeast through much of WI and into the
northern L.P./eastern U.P. of MI. Exceptional WAA within the warm
nose, anomalous column moisture, and a lack of strong dry advection
to offset the latent heat release of freezing should limit the
freezing rain accretion efficiency. However, there is still likely
to be a long duration of freezing rain leading to significant and
impactful icing for which WPC probabilities indicate at least a 70%
chance of 0.1", with a 40-60% chance for at least 0.25" across WI.
Locally, more than 0.5" is possible (10-30% chance) in central WI
but at this time that appears to be more the exception than the
rule. Regardless, considerable impacts from icing are likely as
reflected by the WSSI-P which indicates a 60-80% chance for
moderate impacts.


...Sierra Nevada to the Central Rockies...
Days 1-3...

A shortwave trough is beginning to track into CA today and will
race east through the Great Basin tonight and over the central
Rockies by Wednesday. An impressive plume of Pacific moisture
(NAEFS shows IVT values of at least 99.5 climatological percentile
over the Southwest) will be directed at the Central Rockies with
periods of heavy mountain snow from the Wasatch on east through the
CO Rockies. Snow will be at its heaviest over the CO Rockies and
Wasatch tonight with lingering heavy snowfall continuing into
Wednesday. Snow rates will decrease by Wednesday night but some
lingering light mountain snow will continue. WPC probabilities show
high chances (>70%) for additional snowfall >6" in the central and
southern Sierra Nevada through Wednesday. The heaviest snowfall in
the Wasatch will occur above 8,000ft where as much as 6-12" of
snowfall is expected. The snowfall "jackpot" is in the CO Rockies
at/above 9,000ft where snowfall is likely to surpass 12" and may
approach 20" locally.

There is not much of a break in the snowfall as the next closed low
tracking through the Northwest directs yet another anomalous IVT
(200-300 kg/m/s, or above the 90th climatological percentile per
NAEFS) at CA and the Great Basin on Wednesday. Snow levels in the
northern CA ranges (Trinity, Siskiyou, Salmon) drop to as low as
3,000ft) with minor accumulations down to 3,000ft while heavier
totals (amounts surpassing 6") will generally be found at/above
5,000ft. Farther south, the northern Sierra Nevada above 6,000ft
have moderate-to-high chances (50-80%) for snowfall totals >6"
through Wednesday night. This same moisture source works its way
across the Wasatch, Uinta, and Bear River Ranges of UT, including
the southern WY and northern CO ranges by Thursday and lingering
through early Friday. WPC probabilities show moderate-to-high
chances (50-80%) for additional snowfall >8" in the listed UT
ranges with similar probabilities in the Park and Medicine Bow
ranges of WY/CO.

In summary, any significant impacts will be confined to the higher
elevations of these ranges, with one exception being I-80 and US-50 over
the Sierra Nevada where the the WSSI shows Moderate Impact
potential. Most of these mountain ranges east of the Sierra Nevada
are well below normal for cold season snowfall, so while some
travel impacts are possible, the snowfall is also welcomed with
the cold season now well into its "fourth quarter", so to speak.


...Pacific Northwest to the Northern Rockies...
Days 1-3...

A powerful closed upper-low diving southward from the Gulf of
Alaska will be the catalyst for renewed mountain snow in the
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far
east as the Blue Mountains Wednesday afternoon and continuing
through Thursday. The approaching 850-500mb layer heights
associated with the closed low are below the 2.5 percentile per
NAEFS and snow levels will drop as low as 2,000ft Wednesday night
in the Olympics, Cascades, and even as far south as the Siskiyou. A
steady stream of Pacific moisture embedded within SWrly mean layer
flow, suitable for upslope enhancement as well, will also favor
locally heavy snowfall rates in these ranges. Drier air on the
backside of the closed low arrives Thursday afternoon, although
lingering westerly low-level winds should support light-to-
moderate snow in the Cascades for the remainder of the day on
Thursday. Precipitation tapers off east of the Divide by Thursday
night.

Farther east, snow will start Wednesday night and continue through
this forecast period (12Z Fri) over Montana. The closed low will
weaken to an extent, but it remains well intact as it moves east
with healthy upper-level divergence out ahead of the closed low.
In addition, NAEFS shows >90th climatological percentile levels
for 500mb and 700mb mean specific humidity (g/kg), indicating
unusually high moisture content higher up in the atmospheric
column. With a 500mb low track from the WA/OR border ESE across
central ID into central WY, snow will be heaviest on the low's
northern flank across the Blue Mountains, Bitterroots, Absarokas,
Tetons and into the Bighorns. The western MT ranges will also see
moderate snow totals closer to the 700mb low and added assist of
low-level easterly flow that results in upslope enhancement.

WPC 48-hour probabilities for at least 12 inches of snow are high

70%) in the OR Cascades above 4,000ft with at least moderate

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,
but several inches of snow at pass level (Snoqualmie and Stevens)
are expected. To the east, WPC probabilities for at least 12 inches
of snow are moderate-to-high (50-70%) above 7000ft or so. The peaks
of the Blue, Sawtooth, Absaroka, and Tetons have low-to-moderate
odds (30-50%) for snowfall totals topping 18" through Friday.


...Northern New England...
Days 1 & 3...

A pair of sheared 500mb vorticity maxima tracking through northern
New England will be accompanied by a steady stream of 850-300mb
moisture aloft to produce periods of snow over far northern Maine
and a wintry mix of sleet/freezing rain in central Maine today and
tonight. As a wave of low pressure tracks along a warm front
draped over northern New England tonight, additional wintry
precipitation will develop and produce additional snow and ice
accumulations through Wednesday morning. WPC probabilities show at
least moderate chances (>50%) for additional snowfall totals over
4", while central Maine sports at least moderate chances (>50%) for
additional ice accumulations over one-tenth of an inch.

Following a break in the snow and ice Wednesday afternoon and
through much of the day on Thursday,moisture streaming north out
ahead of the Midwest winter storm will be paired with increasing
850-700mb WAA aloft that produces more precipitation. High pressure
over Quebec will help to lock in sub-freezign wet-bulb temps from
the White Mountains on north through interior Maine, allowing for
yet another round of wintry precipitation Thursday afternoon and
lingering through Thursday night. Snow will be the primary
precipitation at the onset in northern Maine, but even northern
Maine will flip over to a wintry mix Thursday night and continue to
contend with freezing rain into Friday morning. Eventually, strong
low-level WAA will erode the sub-freezing temperatures at the
surface and precipitation will changeover to plain rain. Prior to
the changeover to rain, WPC probabilities show low-to-moderate
chances (30-50%) for ice accumulations over one-tenth of an inch
over the White Mountains and along the Maine/Quebec border. Similar
are present for >4" of snowfall over far northern Maine through
Friday morning.

...Northern Plains...
Day 3...

No rest for the weary in the Northern Plains, as the departure of
one winter storm only means the arrival of yet another storm system
on Friday. A slow moving 500mb closed low over WY will generate
healthy PVA aloft and increased 700mb Q-vector convergence over the
northern High Plains. Snow will already be falling over central MT
and the Big Horns Thursday night, but as a surface low strengthens
along the KS/NE border Friday morning, 850-700mb WAA to the north
of the low will support banded precipitation on the northern flank
of the 500mb low. Guidance is in good agreement on the presence of
a very moist 700-300mb column, although exact placement of the
heaviest QPF axis is still unclear. Still, hazard-focused guidance
such as the ECMWF-EFI is showing a signal up to 0.8 for QPF from
the MT/WY border on east to SD. This product shows the potential
for an unusual amount of QPF at this storm's disposal, with thermal
profiles that do support snow on the storm's northern and western
flanks.

WPC probabilities show a large swath of at least moderate-chance
probabilities (>50%) for >4" of snow from northeast WY and southern
MT through northern SD and southern ND. Given the slow progression
of the upper low and likely banding associated with this storm,
snowfall rates >1"/hr for prolonged windows could result in
localized amounts exceeding 12". This is evident in WPC
probabilities that show low chances for >12" totals in northwest SD
and southwest ND. Lastly, there is the potential for some icing
closer to the warm front farther east. WPC probabilities show low-
to-moderate chances (30-50%) for ice accumulations over one-tenth
of an inch in southeast SD and southwest MN. Residents in the
Northern Plains should continue to monitor the forecast closely as
any subtle change in track or change in the storm's intensity could
mean notable changes to expected snowfall totals.


Mullinax/Weiss




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FOUS11 KWBC 311926
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 PM EDT Tue Mar 31 2026

Valid 00Z Wed Apr 01 2026 - 00Z Sat Apr 04 2026


...Northern Plains through the Great Lakes...
Days 1-3...

...Significant late season snow and freezing rain likely to create
substantial impacts through mid-week...

Late season winter storm will begin on Wednesday as a lee side low
pressure system develops across eastern Colorado. This low will
develop in response to a shortwave which will emerge from the
Pacific over California and then sharpen as it moves across the
Four Corners Wednesday. This shortwave is expected to then develop
a negative tilt as it pushes into the Upper Midwest Thursday before
exiting into Canada by Friday morning. The combination of
impressive downstream divergence ahead of this sharpening
shortwave, followed by height falls and the LFQ of a modest but
strengthening meridionally arcing jet streak will provide
widespread deep layer ascent to help deepen the surface low as it
tracks from Colorado northeast into Michigan.

The challenge for this period primarily revolves around the track
and timing of this low, as there is high confidence in its
development. Over the past 4 cycles of the ECENS and GEFS, the
surface low clusters have become more consolidated, but continue to
feature a subtle N/NW trend. This is in response to a small
deepening trend in the upper pattern, although the EC-AIFS has been exceptionally consistent with its track, so while the NW trend may
continue, it appears that is slowing and beginning to consolidate
leading to higher confidence overall.

As this low develops and tracks northeast, impressive moisture will
spread northward to support a large swath of all p-types. An
impressive IVT plume (>90% for 250 kg/m/s pushing well into the
Rockies) will support upper level moisture into the system, while
low-level moisture fueled by increasing WAA out of the Gulf help to
saturate the low-levels. The accompanying theta-e ridge emerging
northward will help expand the precipitation shield thanks to PW
anomalies that surge above the 99th percentile according to NAEFS.
This will result in periods of heavy precipitation, first across
the Dakotas Wednesday morning and then expanding eastward within=20
the WAA plume, reaching Michigan by Thursday morning, with
precipitation continuing through Thursday night, potentially
Friday morning across northern MN, before ending across the area.

In the locations that receive mostly snow, which is expected to be
the Dakotas, and the northern half of Minnesota, heavy
accumulations appear likely. In this area, snowfall rates of 1"/hr
appear likely through both WAA and then deformation on the NW side
of the low as it deepens, leading to 48-hr WPC probabilities that=20
are moderate (50-70%) for at least 4 inches of snow, with locally
more than 8 inches possible (10-30%) from the Buffalo Ridge through
the Arrowhead of MN and the western U.P. of MI. Lighter snowfall of
2-4" is likely south/east of this axis including the northern
suburbs of the Twin-Cities and Green Bay, where heavy snow will
develop but rapidly changeover to a mix and then rain, leading to
lesser snowfall.

The most substantial impacts from this event may be due to freezing
rain rather than ice. Although the Canadian high pressure over
Ontario will retreat quickly, antecedent wet-bulb temperatures are
well below freezing (in the low to mid 20s) due to very dry
dew point temperatures. Although these will slowly warm as the
impressive warm nose surges northward, there is likely to be an
extended period of freezing rain (after a period of snow and sleet)
from the IA/MN border northeast through much of WI and into the
northern L.P./eastern U.P. of MI. Exceptional WAA within the warm
nose, anomalous column moisture, and a lack of strong dry advection
to offset the latent heat release of freezing should limit the
freezing rain accretion efficiency. However, there is still likely
to be a long duration of freezing rain leading to significant and
impactful icing for which WPC probabilities indicate at least a 70%
chance of 0.1", with a 40-60% chance for at least 0.25" across WI.=20
Locally, more than 0.5" is possible (10-30% chance) in central WI=20
but at this time that appears to be more the exception than the=20
rule. Regardless, considerable impacts from icing are likely as=20
reflected by the WSSI-P which indicates a 60-80% chance for=20
moderate impacts.

Key Messages for this winter storm have been initiated. A link to
view the Key Messages are below.=20


...Sierra Nevada to the Central Rockies...
Days 1-3...

A shortwave trough is beginning to track into CA today and will
race east through the Great Basin tonight and over the central=20
Rockies by Wednesday. An impressive plume of Pacific moisture
(NAEFS shows IVT values of at least 99.5 climatological percentile
over the Southwest) will be directed at the Central Rockies with
periods of heavy mountain snow from the Wasatch on east through the
CO Rockies. Snow will be at its heaviest over the CO Rockies and
Wasatch tonight with lingering heavy snowfall continuing into
Wednesday. Snow rates will decrease by Wednesday night but some=20
lingering light mountain snow will continue. WPC probabilities show
high chances (>70%) for additional snowfall >6" in the central and
southern Sierra Nevada through Wednesday. The heaviest snowfall in
the Wasatch will occur above 8,000ft where as much as 6-12" of
snowfall is expected. The snowfall "jackpot" is in the CO Rockies
at/above 9,000ft where snowfall is likely to surpass 12" and may
approach 20" locally.=20

There is not much of a break in the snowfall as the next closed low
tracking through the Northwest directs yet another anomalous IVT
(200-300 kg/m/s, or above the 90th climatological percentile per
NAEFS) at CA and the Great Basin on Wednesday. Snow levels in the
northern CA ranges (Trinity, Siskiyou, Salmon) drop to as low as
3,000ft) with minor accumulations down to 3,000ft while heavier
totals (amounts surpassing 6") will generally be found at/above
5,000ft. Farther south, the northern Sierra Nevada above 6,000ft
have moderate-to-high chances (50-80%) for snowfall totals >6"
through Wednesday night. This same moisture source works its way
across the Wasatch, Uinta, and Bear River Ranges of UT, including
the southern WY and northern CO ranges by Thursday and lingering
through early Friday. WPC probabilities show moderate-to-high
chances (50-80%) for additional snowfall >8" in the listed UT
ranges with similar probabilities in the Park and Medicine Bow=20
ranges of WY/CO.=20

In summary, any significant impacts will be confined to the higher
elevations of these ranges, with one exception being I-80 and US-50 over
the Sierra Nevada where the the WSSI shows Moderate Impact
potential. Most of these mountain ranges east of the Sierra Nevada
are well below normal for cold season snowfall, so while some
travel impacts are possible, the snowfall is also welcomed with=20
the cold season now well into its "fourth quarter", so to speak.=20


...Pacific Northwest to the Northern Rockies...
Days 1-3...

A powerful closed upper-low diving southward from the Gulf of=20
Alaska will be the catalyst for renewed mountain snow in the=20
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far=20
east as the Blue Mountains Wednesday afternoon and continuing=20
through Thursday. The approaching 850-500mb layer heights=20
associated with the closed low are below the 2.5 percentile per
NAEFS and snow levels will drop as low as 2,000ft Wednesday night=20
in the Olympics, Cascades, and even as far south as the Siskiyou. A
steady stream of Pacific moisture embedded within SWrly mean layer
flow, suitable for upslope enhancement as well, will also favor=20
locally heavy snowfall rates in these ranges. Drier air on the=20
backside of the closed low arrives Thursday afternoon, although=20
lingering westerly low-level winds should support light-to-=20
moderate snow in the Cascades for the remainder of the day on=20
Thursday. Precipitation tapers off east of the Divide by Thursday
night.

Farther east, snow will start Wednesday night and continue through
this forecast period (12Z Fri) over Montana. The closed low will
weaken to an extent, but it remains well intact as it moves east
with healthy upper-level divergence out ahead of the closed low.
In addition, NAEFS shows >90th climatological percentile levels
for 500mb and 700mb mean specific humidity (g/kg), indicating
unusually high moisture content higher up in the atmospheric
column. With a 500mb low track from the WA/OR border ESE across=20
central ID into central WY, snow will be heaviest on the low's
northern flank across the Blue Mountains, Bitterroots, Absarokas,=20
Tetons and into the Bighorns. The western MT ranges will also see=20
moderate snow totals closer to the 700mb low and added assist of
low-level easterly flow that results in upslope enhancement.

WPC 48-hour probabilities for at least 12 inches of snow are high=20

70%) in the OR Cascades above 4,000ft with at least moderate=20

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The=20
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,=20
but several inches of snow at pass level (Snoqualmie and Stevens)=20
are expected. To the east, WPC probabilities for at least 12 inches
of snow are moderate-to-high (50-70%) above 7000ft or so. The peaks
of the Blue, Sawtooth, Absaroka, and Tetons have low-to-moderate
odds (30-50%) for snowfall totals topping 18" through Friday.


...Northern New England...
Days 1 & 3...

A pair of sheared 500mb vorticity maxima tracking through northern
New England will be accompanied by a steady stream of 850-300mb=20
moisture aloft to produce periods of snow over far northern Maine=20
and a wintry mix of sleet/freezing rain in central Maine today and=20
tonight. As a wave of low pressure tracks along a warm front
draped over northern New England tonight, additional wintry
precipitation will develop and produce additional snow and ice
accumulations through Wednesday morning. WPC probabilities show at
least moderate chances (>50%) for additional snowfall totals over
4", while central Maine sports at least moderate chances (>50%) for
additional ice accumulations over one-tenth of an inch.

Following a break in the snow and ice Wednesday afternoon and
through much of the day on Thursday,moisture streaming north out=20
ahead of the Midwest winter storm will be paired with increasing=20
850-700mb WAA aloft that produces more precipitation. High pressure
over Quebec will help to lock in sub-freezign wet-bulb temps from
the White Mountains on north through interior Maine, allowing for
yet another round of wintry precipitation Thursday afternoon and
lingering through Thursday night. Snow will be the primary
precipitation at the onset in northern Maine, but even northern
Maine will flip over to a wintry mix Thursday night and continue to
contend with freezing rain into Friday morning. Eventually, strong
low-level WAA will erode the sub-freezing temperatures at the=20
surface and precipitation will changeover to plain rain. Prior to
the changeover to rain, WPC probabilities show low-to-moderate
chances (30-50%) for ice accumulations over one-tenth of an inch
over the White Mountains and along the Maine/Quebec border. Similar
are present for >4" of snowfall over far northern Maine through=20
Friday morning.=20

...Northern Plains...
Day 3...

No rest for the weary in the Northern Plains, as the departure of
one winter storm only means the arrival of yet another storm system
on Friday. A slow moving 500mb closed low over WY will generate
healthy PVA aloft and increased 700mb Q-vector convergence over the
northern High Plains. Snow will already be falling over central MT
and the Big Horns Thursday night, but as a surface low strengthens
along the KS/NE border Friday morning, 850-700mb WAA to the north
of the low will support banded precipitation on the northern flank
of the 500mb low. Guidance is in good agreement on the presence of
a very moist 700-300mb column, although exact placement of the
heaviest QPF axis is still unclear. Still, hazard-focused guidance
such as the ECMWF-EFI is showing a signal up to 0.8 for QPF from
the MT/WY border on east to SD. This product shows the potential
for an unusual amount of QPF at this storm's disposal, with thermal
profiles that do support snow on the storm's northern and western
flanks.

WPC probabilities show a large swath of at least moderate-chance
probabilities (>50%) for >4" of snow from northeast WY and southern
MT through northern SD and southern ND. Given the slow progression
of the upper low and likely banding associated with this storm,
snowfall rates >1"/hr for prolonged windows could result in
localized amounts exceeding 12". This is evident in WPC
probabilities that show low chances for >12" totals in northwest SD
and southwest ND. Lastly, there is the potential for some icing
closer to the warm front farther east. WPC probabilities show low-
to-moderate chances (30-50%) for ice accumulations over one-tenth
of an inch in southeast SD and southwest MN. Residents in the=20
Northern Plains should continue to monitor the forecast closely as=20
any subtle change in track or change in the storm's intensity could
mean notable changes to expected snowfall totals.=20


Mullinax/Weiss



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9LLptld8EifLcDw_r2bJ3bvA7Ix7k7UFGRS-52nXqJM6H= 29OpvGj5Pog1zl0CyJJt8GyvWsRhe_vxt0JlHmd3rExL5I$=20



$$

=3D =3D =3D
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--- SBBSecho 3.28-Linux
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FOUS11 KWBC 010826
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
426 AM EDT Wed Apr 1 2026

Valid 12Z Wed Apr 01 2026 - 12Z Sat Apr 04 2026


...Northern Plains through the Great Lakes...
Days 1-2...

...Significant late-season snow and freezing rain likely to create
substantial impacts...

Late-season winter storm will begin tonight as an exiting=20
shortwave out of the Rockies spurs a lee-side low pressure system=20
this afternoon. This shortwave is expected to then develop a=20
negative tilt as it pushes into the Upper Midwest Thursday before=20
exiting into Canada by Friday morning. The combination of=20
impressive downstream divergence ahead of this sharpening shortwave
followed by height falls and the LFQ of a modest but strengthening
meridionally arcing jet streak will provide widespread deep-layer=20
ascent to help strengthen the surface low as it tracks from=20
Colorado northeastward into Michigan.

Impressive moisture will spread northward to support a large swath
of all p-types that move through time during the event. Ample=20
upper-level moisture from the southwest and low-level moisture=20
fueled by increasing WAA out of the Gulf will saturate the low=20
levels. The accompanying theta-e ridge emerging northward will help
expand the precipitation shield thanks to PW anomalies that surge=20
above the 99th percentile according to NAEFS. This will result in=20
periods of heavy precipitation, first across the Dakotas this=20
morning and then expanding eastward within the WAA plume, reaching=20
Michigan by Thursday morning. Precipitation will continue through=20
Thursday night and eventually end from southwest to northeast on=20
Friday morning.

In the locations that receive mostly snow, which is expected to be
mostly in the northern half of Minnesota, modest to locally heavy=20 accumulations appear likely. In this area, snowfall rates of 1"/hr=20
are likely via deformation on the NW side of the low as it deepens,
leading to 48-hr WPC probabilities that are moderate/high (50-80%)
for at least 4 inches of snow, with locally more than 8 inches=20
possible (10-30%) from the Buffalo Ridge through the Arrowhead of=20
MN (40-60%) and into the Keweenaw Peninsula. Lighter snowfall of=20
2-4" is likely south/east of this axis north of the Twin-Cities and
Green Bay. In these regions, heavy snow will develop but rapidly=20
change over to a wintry mix and then rain, leading to lesser=20
snowfall.

The most substantial impacts from this event may be due to=20
freezing rain. Although the Canadian high pressure over Ontario=20
will retreat quickly, antecedent wet-bulb temperatures are well=20
below freezing (in the low to mid 20s this morning) due to very dry
dew point temperatures. Although these will slowly warm as the=20
impressive warm nose surges northward, there is likely to be an=20
extended period of freezing rain (after a period of snow and sleet)
from the eastern SD and along/north of the IA/MN border through=20
much of WI and into the northern L.P./eastern U.P. of MI.=20
Exceptional WAA within the warm nose, anomalous column moisture,=20
and a lack of strong dry advection to offset the latent heat=20
release of freezing should limit the freezing rain accretion=20
efficiency. However, there is still likely to be a long duration of
freezing rain leading to significant and impactful icing for which
WPC probabilities indicate at least a 70% chance of 0.1", with a=20
40-70% chance for at least 0.25" across WI. Locally, more than 0.5"
is possible (10-40% chance) in central WI. Considerable impacts=20
from icing are likely as reflected by the WSSI that shows=20
widespread moderate to locally major impacts.=20

Please see a link to view the Key Messages at the end of this=20
discussion.



...CA/Great Basin to the Central Rockies...
Days 1-2...

A shortwave trough over the Great Basin this morning will continue
eastward today. An impressive plume of Pacific moisture (NAEFS=20
shows IVT values of at least 99.5 climatological percentile over=20
the Southwest) will be directed at the Central Rockies with periods
of heavy mountain snow from the Wasatch on east through the CO=20
Rockies. Snow will wane from west to east today over NV/UT but=20
continue over the CO Rockies through the day and diminishing=20
overnight. WPC probabilities for an additional 6 inches of snow are

50% over the Wasatch and Uintas. Over the CO Rockies, WPC=20

probabilities for at least an additional 12 inches of snow are >50%
above 10,000ft.=20

There is not much of a break in the snowfall as the next closed=20
low tracking through the Northwest directs yet another anomalous=20
IVT (200-300 kg/m/s, or above the 90th climatological percentile=20
per NAEFS) at CA and the Great Basin starting later today. Snow=20
levels in the northern CA ranges (Trinity, Siskiyou, Salmon) drop=20
to as low as 3,000ft with minor accumulations. Heavier totals=20
(amounts surpassing 6") will generally be found at/above 5,000ft.=20
Farther south, the northern Sierra Nevada above 6,000ft have=20 moderate-to-high chances (50-80%) for snowfall totals >6" through=20
tomorrow morning. This same moisture source works its way across=20
the Wasatch, Uinta, and Bear River Ranges of UT, including the=20
southern WY and northern CO ranges by Thursday and lingering=20
through early Friday. WPC probabilities show moderate-to- high=20
chances (50-80%) for additional snowfall >8" in the listed UT=20
ranges with similar probabilities in the Park and Medicine Bow=20
ranges of WY/CO.=20

In summary, any significant impacts will be confined to the higher
elevations of these ranges, with one exception being I-80 and=20
US-50 over the Sierra Nevada where the the WSSI shows Moderate=20
Impact potential. Most of these mountain ranges east of the Sierra=20
Nevada are well below normal for cold season snowfall, so while=20
some travel impacts are possible, the snowfall is also welcomed=20
with the cold season trying to make up for lost time.=20


...Pacific Northwest to the Northern Rockies...
Days 1-2...

A powerful closed upper-low diving southward from the Gulf of=20
Alaska will be the catalyst for renewed mountain snow in the=20
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far=20
east as the Blue Mountains this afternoon and continuing through=20
Thursday. The approaching 850-500mb layer heights associated with=20
the closed low are below the 2.5 percentile per NAEFS and snow=20
levels will drop as low as 2,000ft Wednesday night in the Olympics,
Cascades, and even as far south as the Siskiyou. A steady stream=20
of Pacific moisture embedded within SWrly mean layer flow, suitable
for upslope enhancement as well, will also favor locally heavy=20
snowfall rates in these ranges. Drier air on the backside of the=20
closed low arrives Thursday afternoon, although lingering westerly=20
low-level winds should support light-to-moderate snow in the=20
Cascades for the remainder of the day on Thursday. Precipitation=20
tapers off east of the Divide by Thursday night.

Farther east, snow will start tonight and continue through Friday=20
over Montana. The closed low will weaken to an extent, but it=20
remains well intact as it moves east with healthy upper-level=20
divergence out ahead of the closed low. In addition, NAEFS shows=20

90th climatological percentile levels for 500mb and 700mb mean=20

specific humidity (g/kg), indicating unusually high moisture=20
content higher up in the atmospheric column. With a 500mb low track
from the WA/OR border ESE across central ID into central WY, snow=20
will be heaviest on the low's northern flank across the Blue=20
Mountains, Bitterroots, Absarokas, Tetons and into the Bighorns.=20
The western MT ranges will also see moderate snow totals closer to=20
the 700mb low and added assist of low-level easterly flow that=20
results in upslope enhancement.

WPC 48-hour probabilities for at least 12 inches of snow are high=20

70%) in the OR Cascades above 4,000ft with at least moderate=20

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The=20
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,=20
but several inches of snow at pass level (Snoqualmie and Stevens)=20
are expected. To the east, WPC probabilities for at least 12 inches
of snow are moderate-to-high (50-70%) above 7000ft or so. The=20
peaks of the Blue, Sawtooth, Absaroka, and Tetons have low-to-
moderate chances (30-50%) for snowfall totals in excess of 18"=20
through Friday.


...Northern New England...
Day 2...

Moisture streaming north out ahead of the Midwest winter storm=20
will be paired with increasing 850-700mb WAA aloft that produces=20
another round of precipitation. High pressure over Quebec will help
to lock in sub-freezign wet bulb temps from the White Mountains=20
northward through interior Maine, allowing for yet another mixed=20
wintry precipitation Thursday afternoon and lingering through=20
Thursday night. Snow will be the primary precipitation at the onset
in northern Maine, but even there it will flip over to a wintry=20
mix Thursday night with both sleet and freezing rain into Friday=20
morning. Eventually, strong low-level WAA will erode the sub-
freezing temperatures at the surface and precipitation will change=20
over to plain rain late Friday before ending overnight. Prior to=20
the changeover to rain, WPC probabilities for at least a tenth of=20
an inch of ice are moderate (40-60%) over the White Mountains and=20
along the northwestern Maine/Quebec border. Snow will really be=20
limited to just the Allagash where WPC probabilities for at least 4
inches are 20-40%.=20


...Northern Plains to the Upper Midwest...
Day 2.5-3...

The relatively progressive pattern across the CONUS will introduce
another round of potentially impactful snow to the Northern Plains
to the Upper Midwest Friday into Saturday. A slower moving 500mb=20
closed low over WY will generate healthy PVA aloft and increased=20
700mb Q-vector convergence over the northern High Plains early=20
Friday. Snow will already be falling over central MT and the Big=20
Horns Thursday night, but as a surface low strengthens along the=20
KS/NE border Friday morning, 850-700mb WAA to the north of the low=20
will support banded precipitation on the northern flank of the=20
500mb low. Guidance is in good agreement on the presence of a very=20
moist 700-300mb column, although exact placement of the heaviest=20
QPF axis is still unclear. The area of low pressure will track=20
northeastward through Iowa and cross into WI by the end of this=20
forecast period (12Z Sat), though there is spread in the speed of=20
the low. Snow will remain on the northwest side of the low over the
Dakotas to northern MN but an area of mixed precip (sleet/freezing
rain) is again likely over parts of southern MN into WI and the=20
U.P. of Michigan.=20

WPC probabilities show a large swath of at >50% probability for at
least 4 inches of snow from northeast WY and southern/southeastern
MT through northern SD and southern ND east-northeastward to=20
northern MN. Given the slower progression of the upper low and=20
likely banding associated with this storm, snowfall rates >1"/hr=20
for a prolonged period could result in localized amounts exceeding=20
12" -- WPC probabilities show 20-40% chances in southern ND into=20
northern SD. Farther east, WPC probabilities for at least a tenth=20
of an inch of ice are 10-40% over southeast SD/southwest MN but=20
40-60% over northern WI into the U.P. of Michigan where most of the precipitation will fall overnight Friday into early Saturday.=20
Changes to the forecast are likely but this system will likely have
impacts for much of the region, especially those who see a wintry=20
mix from the prior system later today/Thursday.=20


Fracasso/Mullinax/Weiss



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!7LXNvgEotodsiPtRLncNZZFH7w0ysb5ByUQIYWixIQ6yv= -LQ6D73B2VQP6jitBqGvh-v6DyvnioWBSFVeEppxkkRe5Q$=20



$$

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--- SBBSecho 3.28-Linux
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FOUS11 KWBC 012006
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
406 PM EDT Wed Apr 1 2026

Valid 00Z Thu Apr 02 2026 - 00Z Sun Apr 05 2026


...Northern Plains through the Great Lakes...
Days 1-2...

...Significant late-season snow and freezing rain likely to create
substantial impacts...

Significant winter storm begins tonight as a low pressure develops
in the lee of the Colorado Rockies and then tracks northeast into
the Upper Midwest and Great Lakes, reaching Ontario Friday
afternoon. This system is driven by a shortwave that will be moving
atop the Central Rockies Thursday morning and amplify into a
negatively tilted trough as it lifts northeast into Ontario by
Friday. The trends in the guidance have been for this shortwave to
be a bit deeper, leading to sharper height falls combined with the
LFQ of a modest but meridionally arcing jet streak. This will
produce significant deep layer ascent to deepen the surface low as
it tracks northeast, and the guidance has clustered to a slightly
slower but stronger surface low today.

As this low tracks northeast, impressive column PW will manifest=20
across the Upper Midwest in response to dual moisture streams
interacting into the region. Residual IVT from the Pacific will
continue to push inland with the shortwave over the Rockies, and
IVT probabilities for >250 kg/m/s remain high, bringing elevated
moisture into the region on the 700-500mb flow. In the lower
levels, return flow out of the Gulf begins to intensify as 850mb=20
winds surge northward, spreading a pronounced theta-e ridge
northward into the system. The overlap of these two moisture
streams will create PW anomalies that are above the 99th percentile
of the CFSR climatology according to NAEFS, and this is likely to
be a very wet early-spring system.=20

The primary driver of the associated precipitation will be
intensifying isentropic ascent, especially along the 290-295K
surfaces where mixing ratios of 4-5 g/kg will support heavy
precipitation anywhere within the system. The strongest ascent will
be where the 850mb winds and accompanying WAA produce intense fgen,
and this will result in an above-freezing warm nose surging
northward. The surface high pressure responsible for the cold/dry
antecedent airmass will retreat rapidly to the northeast, and=20
regional soundings indicate that a lack of sufficient dry-bulb=20
advection will promote a rapid transition from snow to freezing=20
rain, especially for eastern MN through MI, with snow remaining the
primary p-type for northern MN and the eastern Dakotas.

In the snow areas, heavy snow rates will develop as fgen=20
strengthens and then a modest deformation axis develops to drive=20
ascent into the modest TROWAL which will form as the theta-e ridge=20
wraps cyclonically into the system. With elevated PWs in place,=20
this should result in rates approaching 1"/hr at times as supported
by the WPC prototype snowband tool, and any local banding will
enhance the duration of snowfall. Overall snowfall amounts will be
modest due to the rapid progression of this system, but a slightly
slower track and some heavier snowfall rates will still support a
high risk (>70% chance) for more than 4 inches of snow from eastern
ND through northern MN and the Arrowhead, with locally as much as 8
inches possible (10-30% chance) across this same axis.

Farther east, the primary p-type will likely be freezing rain as
the warm air aloft floods northward without any strong forcing to
prevent this. The cold layer beneath the warm nose is quite deep,
above the 75th% for cold-layer depth for freezing rain, so there
may be some considerable sleet before changeover to freezing rain,
with 0.5" to 1.0" of sleet possible for northern WI and the U.P.=20
of MI. However, the greatest impacts are likely from the Buffalo=20
Ridge through the Twin Cities, into central WI, and the northern=20
L.P. of MI where WPC probabilities indicate a moderate to high risk
(50-90% chance) of at least 0.1" of ice, with 0.25" or even 0.5"=20
possible (50% and 20% respectively) across parts of WI.

Key Messages are in effect for this system and are linked below
(Key Messages #1).


...Northern New England...
Day 2...

Moisture streaming northward ahead of the large Midwest winter
storm will surge into New England Thursday night and Friday on
persistent warm advection. As the WAA intensifies through the
850-700mb layer, precipitation will expand from Vermont into Maine
in response to the maximizing fgen. During precipitation onset,
wet-bulb temperatures will be below freezing (with a full below-
freezing column across Maine) as Canadian high pressure only slowly
retreats to the northeast. As this high retreats and the WAA
continues, the accompanying warm nose should surge all the way into
Canada causing a p-type transition from snow to sleet to freezing
rain, and eventually rain. Before the changeover, a period of heavy
snow with rates around 1"/hr are possible, primarily just for
northern Maine, leading to WPC probabilities that are 50-70% for at
least 4 inches of snowfall. Farther south, from the White Mountains
of NH into the higher terrain of northern/central ME, a period of
freezing rain is expected which will lead to a moderate risk
(30-50% chance) of at least 0.1" of ice accumulation. Although the
snowfall by itself, or the icing by itself, may not result directly in warning-level impacts, the combination of a period of heavy snow,
followed by sleet, followed by freezing rain, will create
treacherous travel and some elevated snow load on trees/wires
leading to substantial impacts across parts of northern ME.

While the heaviest snow and ice are expected only in the higher=20
terrain or highest latitudes of northern New England, light snow=20 accumulations and light icing is expected for much of northern and=20
central New England before p-type transitions to all rain by late=20
Friday morning.


...Pacific Northwest/Sierra through Northern/Central Rockies...=20
Days 1-2...

Active winter weather continues through late-week as an anomalously
deep trough digs across the Northwest bringing widespread heavy
snow to the terrain through Friday.

At the beginning of the period /00Z Thursday/ a shortwave will be
positioned off the WA coast, with impressive confluent flow to its
south driving moisture onshore as reflected by IVT probabilities
for at least 250 kg/m/s exceeding 90% from the GEFS/ECENS lifting
into WA/OR D1. This shortwave is progged to amplify into a potent
closed low and dig into the Pacific and Interior Northwest by
Thursday morning, and then continue to move slowly but steadily
eastward with impressive height falls reaching the Northern and
Central Rockies by Friday morning. This feature will be expansive
and amplified, reflected by a large swath of 500mb heights falling
below the 10th percentile within the CFSR climatology according to
NAEFS.=20

As this closed low dives E/SE through the area, the accompanying
Pacific jet streak (which will be weakening from 140 kts early D1
to 110 kts late D1) will continue to be favorably positioned to
enhance deep layer lift through its diffluent LFQ, resulting in
sufficient ventilation for surface low development tracking from WA
to WY by early D2. This low will also drag a strong cold front
behind it, bringing colder temperatures and lowering snow levels
through the event.

With significant deep layer ascent in place, and moisture
increasing through the onshore flow from the Pacific, precipitation
is expected to be widespread Thursday into Friday. Initially, snow
levels are expected to be between 6000-8000 ft ahead of the cold
front, but will fall sharply as it tracks southeast, dropping to as
low as 2500-3000 ft across much of the region. It appears that the
heaviest precipitation will occur along and ahead of this front, so
the heaviest snowfall should remain at the mid-to-higher
elevations. However, some light snow is expected down to many of
the passes as the cold front progresses eastward, leading to
widespread hazardous travel before precipitation wanes Friday
morning.

On D1 /00Z Thu to 00Z Fri/ WPC probabilities indicate the highest
snowfall potential will be across the northern Sierra and Oregon
Cascades where the moisture will be directed orthogonally into the
terrain, leading to upslope enhancement, with additional
significant spillover leading to heavy snow as well into the=20
Salmon River/Sawtooth Ranges, and the Tetons/Wind Rivers. In these=20
areas, WPC probabilities are high (>70%) for at least 8 inches of=20
snow, with locally 12-18" possible in the highest terrain.=20
Elsewhere on D1, WPC probabilities suggest a high risk for at least
4 inches for the WA Cascades, much of the Northern Rockies, and=20
surrounding terrain as far south as the Ruby Mountains of NV,=20
Uintas of UT, and even into the Park Range and portions of the CO=20
Rockies.

By D2, the focus of heaviest snow shifts well to the interior,
leaving heavy snow only across the Northern and Central Rockies as
a significant lee cyclone develops across WY (more on this in the
section below). Additional snowfall D2 has a high risk (>70%
chance) of at least 6 inches across the Absarokas and Big Horns,
with lower probabilities extending into the Little Belts, Lewis
Range, and portions of the CO Rockies and Laramie range. The
heaviest snowfall D2 should be above 4000 ft.


...Northern Plains to the Upper Midwest...
Day 2.5-3...

...Significant late-season snow and freezing rain likely to create
substantial impacts...

A slow moving 500mb closed low over WY will generate healthy PVA=20
aloft and increased 700mb Q-vector convergence over the northern=20
High Plains on Friday. Snow will already be falling over central=20
MT and the Big Horns Thursday night, but as a surface low=20
strengthens along the KS/NE border Friday morning, 850-700mb WAA to
the north of the low will support banded precipitation on the=20
northern flank of the 500mb low. Guidance is in good agreement on=20
the presence of a very moist 700-300mb column with strong vertical
velocities aloft supporting snowfall rates of 1-2"/hr. On the=20
eastern flank of the storm, freezing rain and sleet will be more=20
prominent from central MN on north and east into northern WI and=20
the U.P. of MI. Snow will persist over northern MN into Saturday
with any ongoing ice changing over to snow in northern WI and the
western U.P. of MI. Cyclonic flow on the back side of the storm
will keep periods of snow in the forecast across the U.P. of MI
through early Sunday morning.=20

WPC probabilities show a large swath of at >50% probability for at
least 8 inches of snow from southern ND and norther SD on east into
northern MN. Where the pivoting deformation zone forms in southern
ND and northern SD sets up will determine who sees the most snow.
WPC probabilities show moderate chances (40-60%) for >12" of snow
in south-central ND and north-central SD at this time. In fact,
there are low chance probabilities (10-30%) for localized amounts
surpassing 18". Farther east, WPC probabilities for at least a=20
tenth of an inch of ice show moderate chances (40-60%) over=20
southeast SD/southwest MN but high chances (>70) over northern WI=20
and the U.P. of MI.. It is in northern WI and the U.P. of MI where
there are concerns for prolonged affects between the two winter
storms late week, given WPC probabilities show at least moderate
chances (>50%) for additional ice accumulations over one-quarter
inch. The Day 3 WSSI currently shows Moderate Impacts in southern=20
ND and northern SD due to the heavy snowfall, as well as in
northern WI and the U.P. of Michigan due to ice accumulations.


Weiss/Mullinax




...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!6kBIVWskrvb06emiItPe0iWe3MYfSSYFjc26_7QOJyA5S= 3uBhNh0vi7LP9MuEdmRbLblHu2pDu2m_865te55uqGdjmQ$=20

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!6kBIVWskrvb06emiItPe0iWe3MYfSSYFjc26_7QOJyA5S= 3uBhNh0vi7LP9MuEdmRbLblHu2pDu2m_865te55qkvw7og$=20



$$

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FOUS11 KWBC 020730
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
330 AM EDT Thu Apr 2 2026

Valid 12Z Thu Apr 02 2026 - 12Z Sun Apr 05 2026


...Northern Plains through the Great Lakes...
Day 1...

...First of back-to-back systems will bring significant late-
season snow and freezing rain with substantial impacts...

The first in a pair of powerful late-season winter storms will=20
continue to develop as an amplifying, negatively-tilted trough=20
lifts northeast from the central Plains this morning. This system=20
is expected to continue its northeastward track, reaching the upper
Mississippi Valley and western Great Lakes by this evening before=20
lifting into western Ontario by early tomorrow. Fueled by both Gulf
and Pacific moisture, this system is expected to produce a lengthy
stripe of significant ice, bordered by heavy snow to the north.=20

Supported by a warm nose of air aloft, snow transitioning to sleet
and freezing rain is expected from eastern South Dakota to=20
northern Michigan. Significant ice accumulations are likely for=20
portions of the region, especially over parts of northern Wisconsin
and Michigan. WPC guidance continues to show probabilities greater
than 70 percent for ice accumulations over 0.10 inch, along with a
greater than 50 percent chance for ice accumulations over 0.25=20
inch over parts of the region through early Friday.

The better chance for heavier snow will center to the north across
the Minnesota Arrowhead, where WPC probabilities show a greater=20
than 70 percent chance for snow accumulations over 4 inches.

Key Messages are in effect for this system and are linked=20
below (Key Messages #1).

...Northern New York and New England...
Days 1-3...

Moisture from the first Midwest storm will surge into New England
tonight. Cold air anchored by Canadian high pressure will initially
support snow before a transition to a wintry mix occurs.=20

Northern Maine is likely to see the longest period of snow, with=20
snow rates of 1 in/hr possible Thursday night into Friday.
WPC probabilities greater than 50 percent for snow accumulations=20
over 4 inches are largely confined to far northern Aroostook=20
County. But even areas this far north are expected to eventually
transition from snow to sleet and freezing rain.

Further to the south, from the Adirondacks to the northern New=20
England mountains, a wintry mix with accumulating ice is more=20
likely. Significant ice accumulations are most likely from the=20
White Mountains into northwestern Maine, where WPC probabilities=20
show a 50-70+ percent chance for ice accumulations over 0.10 inch=20
through midday Friday.=20

As the second system to impact the Midwest lifts northeast, a
second round of snow and ice is expected Saturday night into
Sunday, with most areas quickly transitioning from snow to sleet=20
and freezing rain.


...Pacific Northwest through Northern/Central Rockies...=20
Day 1...

A deep, cold low will continue to move inland over the Northwest=20
this morning, bringing additional snow to the Cascades as the=20
leading edge spreads into the northern Rockies.

Continued onshore flow in the wake of the system will bring=20
additional heavy snow to parts of the Cascades as snow levels=20
plunge behind a sharp cold cold front pressing south and east.

Snow is expected to wane across the Northwest by this evening, but
continue across parts of the northern and central Rockies as the
low moves across the region late today into early Friday.

The heaviest snow accumulations through early Friday are expected
to focus along the northern Rockies from western Montana to
northern Utah. WPC probabilities indicate widespread accumulations
of 6+ inches are likely, with some potential for amounts over a
foot in the higher terrain.=20

...Northern Plains to the Upper Midwest...
Days 2-3...

...Second of back-to-back systems expected to bring additional
heavy snow and icing to portions of the region late week...

As the previously described low moves east of the Rockies, a second
surface low will strengthen over the Central Plains and lift
northeast into the Upper Midwest, bringing a renewed round of=20
heavy banded snow and ice to the Northern Plains and the Upper
Midwest.

Strong lift supported in part by coupled upper jet forcing will
support snowfall rates of 1-2 in/hr across the Northern Plains.
Guidance indicates a more expansive footprint of heavy snow is
likely with this second system. WPC probabilities indicate snow
totals exceeding 8 inches are likely from southeastern North=20
Dakota and northeastern South Dakota to northern Minnesota. Within=20
this area some locations may see a foot or more, with southeastern=20
South Dakota the focus for the highest probabilities in the latest=20
WPC guidance.=20

This storm is expected to deliver another round of freezing rain=20
to portions of the region as well. Once again, parts of northern=20
Wisconsin and Michigan may be affected by the heaviest ice=20
accumulations, compounding impacts generated by the first storm.

Key Messages are in effect for this system and are linked=20
below (Key Messages #2).

Pereira


...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_6aJ3Z3xg2CnJF4rkY-AWX4Enn3OgeTfT3DNOC5hiRfxD= lTjCCRgpwLKxlxl7_SxE0d7PpKnhboR9SgsclN9qCbk3uo$=20

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_6aJ3Z3xg2CnJF4rkY-AWX4Enn3OgeTfT3DNOC5hiRfxD= lTjCCRgpwLKxlxl7_SxE0d7PpKnhboR9SgsclN9cARK9No$=20


$$

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FOUS11 KWBC 021804
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
204 PM EDT Thu Apr 2 2026

Valid 00Z Fri Apr 03 2026 - 00Z Mon Apr 06 2026


...Upper Midwest through the Great Lakes...=20
Day 1...

...First of back-to-back significant late-season winter storms=20
wraps up late tonight into early Friday morning...

Ongoing snow, sleet, and freezing rain associated with a=20
strengthening surface low tracking across the Upper Midwest and=20
northern Great Lakes will continue this evening before ending late=20
tonight into early Friday morning. Freezing rain and icing will=20
mostly be confined to northern WI and the U.P. of Michigan,=20
transitioning to sleet and snow with northern and western extent.=20
Additional ice accumulations of more than 0.1 inches are possible=20
(30-50% chance), leading to storm total icing of as much as 0.5=20
inches, resulting in treacherous travel, and scattered power=20
outages. Colder air wrapping in on the back side of the departing=20
system may allow for some areas predominantly experiencing mixed=20 precipitation to briefly change to snow before ending, but any=20
accumulation would mainly be light with little additional impacts.

The heaviest remaining snow will primarily be focused across=20
northern Minnesota, where an additional 4+ inches is possible
(10-30% chance, locally higher in the Arrowhead) through early=20
Friday morning. Snowfall rates may approach 1" per hour at times,=20
especially this evening, before gradually lessening as the night=20
goes on. Reduced visibility and snow-covered roads will continue to
make travel difficult before conditions gradually improve late=20
tonight into early Friday morning.

Key Messages are in effect for this system and are linked=20
below (Key Messages #1).


...Northern New England...=20
Days 1 & 3...

Two rounds of mixed precipitation will bring modest accumulations
of snow, sleet, and freezing rain to Northern New England through
the weekend, but with considerable impacts across narrow corridors
due to the mixed precipitation types.

The first event will occur D1, generally 06Z/Fri - 00Z/Sat. This
first round of precipitation will be driven by robust WAA surging=20
northward from the Gulf ahead of a significant storm system moving
through the Great Lakes and Ontario, Canada. Initially, this
precipitation will begin as snow in northern VT, NH, and ME as cold
Canadian high pressure slowly retreats, but as the WAA pushes the
warm front northward, especially without any strong dry-bulb
cooling to offset the warmth, p-type transition will rapidly occur
to sleet, freezing rain, and eventually rain for the entire area.
This evolution supports the heaviest accumulations being confined
to just far northern ME where WPC probabilities for snow exceeding
4" are 30-50%. More icing than snow is expected across the rest of
Northern New England as reflected by WPC probabilities for at least
0.01" above 50% for much of the Greens, Whites, and higher
elevations of north-central ME, with locally more than 0.1"=20
possible (30-50%) across western ME and northern NH.

The first system kicks out Friday evening, and Saturday should be
dry across the area. However, a second system will track almost
identically to the first system across the Great Lakes and into
Ontario, spreading moisture into New England along the warm front
through return flow/WAA out of the Gulf. This system will again
encounter a rapidly retreating Canadian high pressure, so once
again a mix of snow, sleet, and freezing rain, is likely, with the
primary difference between the Sunday event and the Friday event
being a slightly warmer starting condition (so less snow). However,
a few inches of snow are again possible across far northern ME (WPC probabilities reach 50-70% for 2"), with locally as much as 0.1"=20
of is possible (30-50%) for the higher elevations of northern NH
and interior western ME.


...Northern/Central Rockies, Northern Plains, & Upper Midwest...=20
Days 1-3...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region into the weekend...

After the first low moves away Friday morning, the region will get
a very brief respite (in some places less than 18 hours) before the
next significant low pressure system impacts the area.

This next low will develop in response to a sharpening mid-level
trough which is expected to become a pronounced closed low with
height anomalies falling below the 10th percentile according to
NAEFS, which will work together with a meridionally arcing jet
streak to produce a deepening cyclone as it tracks from the lee of
the CO Rockies into the Great Lakes. This evolution will result in
widespread significant deep layer ascent through height falls and
jet dynamics, leading to widespread precipitation from the
Northern/Central Rockies, through the Northern Plains, and into the
Great Lakes, before this system departs into Canada Saturday night.

Moisture accompanying this system will also be significant, aided
by both Pacific moisture flooding eastward on modest IVT, and
increasing low-level moisture on southerly WAA emerging from the
Gulf. At the same time, mesoscale ascent will begin to intensify=20
as low to mid level fgen increases to drive omega into a TROWAL
pivoting around the cyclone as the theta-e ridge surges
north/northwest. The deep layer ascent will likely yield widespread
modest precipitation rates for snow and mixed-precipitation, but
the setup does appear to support a pivoting band of heavier
snowfall beneath the TROWAL where deformation maximizes W/NW of the
low. The depth of the upper low supports a strong band, and the WPC
prototype snowband tool indicates more than 1"/hr snowfall rates
being likely from the Dakotas through northern MN.

Where this band pivots the longest, WPC probabilities indicate a
high risk (>70%) for at least 8 inches of snow from far northern SD
through southern ND and into much of northern MN. Within this band,
more than 12 inches (isolated 18 inches) is also possible.
Southeast of this heaviest snowfall where the robust WAA pushes a
warm nose northward to cause p-type transition, WPC probabilities
indicate a high risk (>70%) for at least 0.1 inches of ice from
eastern SD through northern WI and the western U.P. of MI, with
locally significant ice of 0.25 - 0.5 inches possible (30-50%) in
far northern WI and into the U.P. This ice and snow falling atop
areas impacted from storm #1, will likely lead to prolonged
significant impacts to travel and infrastructure, including power
outages.

In addition, and primarily on D1 as the storm begins to get
organized across the Plains, mountain snow will be widespread for=20
the Northern and Central Rockies. This snow will be supported by
onshore Pacific moisture and accompanying mid-level ascent, with
local enhancement likely as a cold front pushes east leading to
upslope flow. Snow levels will fall to around 3000-4000 ft,
bringing considerable impacts to many areas passes, and WPC
probabilities for at least 6 inches are above 70% across the
Absarokas, Tetons, Big Horns and northern CO Rockies.

Key Messages are in effect for this system and are linked=20
below (Key Messages #2).

Weiss/Miller



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_kXLUFm19M7lezQiGLwoz158Zcumg8VVmmWeZuDZtsiuw= XYpe0DuBd0rtcNoZyWy-pLW6tm0ys6Z10b05BTXopeNJhY$=20

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_kXLUFm19M7lezQiGLwoz158Zcumg8VVmmWeZuDZtsiuw= XYpe0DuBd0rtcNoZyWy-pLW6tm0ys6Z10b05BTXteiPhjE$=20



$$

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FOUS11 KWBC 030715
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
315 AM EDT Fri Apr 3 2026

Valid 12Z Fri Apr 03 2026 - 12Z Mon Apr 06 2026


...Northern Plains and Upper Midwest...=20
Days 1-2...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region into the weekend...

The second significant late-season winter storm in 48 hours is
currently organizing as a deep closed low tracks across the
northern Rockies this morning. This system, characterized by
anomalously low heights and deep moisture from both the Gulf and
the Pacific, is expected to track east of the northern Rockies to
the upper Great Lakes over the next 36 hours. As the system moves
into the northern Plains, guidance continues to show a band of=20
heavy snow (1+ in/hr rates) developing within the associated
deformation axis later today. As this band pivots over the=20
Dakotas, heavy accumulations are likely. Bands of heavier snow are
expected to begin shifting into northern Minnesota by this evening
and then continue into Saturday before winding down late in the=20
day as the low begins to track east of the Great Lakes. The latest=20
WPC guidance indicates accumulations greater than 8 inches are=20
likely to cover much of the northern third of South Dakota, the=20
southern half of North Dakota, and northern Minnesota from the=20
North Dakota border to the Arrowhead, with embedded totals over a=20
foot expected within this area.

Significant freezing rain is expected on the warmer, eastern flank
of the system. Measurable ice is forecast from eastern South=20
Dakota and northwestern Iowa to northern Michigan, with the most=20
significant accumulations expected across northern Wisconsin and=20
the western U.P. WPC probabilities indicate ice accumulations of=20
0.10-0.25 inch, with locally heavier amounts, are likely across=20
this area.=20

Sandwiched between the axes of heaviest snow and freezing rain will
likely be a stripe of appreciable sleet, with accumulations around
0.5 inch in spots.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Days 1-3...

Two distinct rounds of mixed precipitation, driven by warm air
advection interacting with retreating cold air, will impact the
region today and then over the weekend.

Precipitation will continue to spread north through the morning
across New England, with most areas in northern New England=20
transitioning quickly to sleet and freezing rain after a brief
period of snow. An eventual change to all rain is expected for most
areas by this evening as low pressure over eastern Canada=20
continues to track toward the region.

Precipitation is expected to wane Friday night, with dry=20
conditions likely through Saturday until the system detailed above=20
follows a similar track east of the Great Lakes. Once again, any=20
snow will be short-lived with precipitation quickly changing over=20
to sleet and freezing rain, and then eventually rain as any=20
lingering cold air gives way to warm air rushing north of what is=20
forecast to become an amplified low.

For both rounds, snow accumulations greater than an inch will
likely be mostly confined to far northern Maine, while ice
accumulations, mostly on the order of 0.1 inch or less are expected
from northern New Hampshire through northern Maine.

Pereira

...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_BPWNrw80LbZBtcJYID52HDa1XMmF93rnKTY3YAA4c30j= IPOrR6OSXS1asUK7RutBn9B2v5RoXDWtrjwZO1OY4Px9qU$=20


$$

=3D =3D =3D
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FOUS11 KWBC 031806
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
206 PM EDT Fri Apr 3 2026

Valid 00Z Sat Apr 04 2026 - 00Z Tue Apr 07 2026


...Northern Plains and Upper Midwest...=20
Day 1...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region through Saturday...

Significant late-season winter storm is ongoing this morning across
the Dakotas, and will expand steadily this evening and continue
through Saturday before winding down from SW to NE Saturday night.
This significant low will track northeast from the Central Plains
through the Great Lakes while exhibiting at least modest deepening
thanks to impressive 500mb height falls downstream of a closed low
with height anomalies around the 10th percentile according to NAEFS
ensemble tables.=20

As this upper low and the accompanying surface cyclone track E/NE
through Saturday, downstream moisture advection will intensify
leading to impressive isentropic ascent, especially along the
290-295K surfaces, lifting into the Upper Midwest. Mixing ratios
within these layers of 3-5 g/kg reflect the anomalous moisture=20
being wrapped into the system, and it is likely that precipitation=20
will become increasingly widespread through this evening and into=20
Saturday. At the same time, the accompanying theta-e ridge will=20
wrap cyclonically around the system and lift into a TROWAL, while=20
the impressive upper low forces intense deformation to drive=20
tremendous ascent into the TROWAL. The combination of the deep=20
layer ascent with robust mesoscale forcing will result in banded=20
structures with snowfall rates for which the WPC prototype snowband
tool suggests will reach 1-2"/hr at times, especially from eastern
ND into northern MN where some pivoting of these bands may also=20
occur. This will result in heavy snowfall accumulations, and WPC=20 probabilities indicate a 50-90% chance of at least 8 inches of=20
snow, with locally 12-18" possible (30% chance).

Farther southeast, the strong WAA east of the upper low will cause
a warm nose to push rapidly northward leading to an area of heavy
mixed precipitation including sleet and freezing rain. The regional
forecast soundings from eastern MN through northern WI and into the
western U.P. of MI indicate a deep cold layer beneath this warm
nose, so p-type will likely start as sleet in many areas. However,
warm nose energy rapidly increases leading to a changeover to an
extended period of freezing rain before the dry slot pushes
northward (likely preventing a changeover to rain in some areas).
While sleet accumulations on both shores of Lake Superior may reach
0.5", the more significant hazard is expected to be freezing rain
where WPC probabilities are high (>70%) for at least 0.1" of ice,
and locally there is a moderate risk (30-50%) for 0.25-0.5" of ice
for far northern WI into the western U.P. of MI. This icing could
be damaging, causing power outages and tree damage, and will likely
exacerbate and prolong impacts ongoing from the ice/snow which
occurred with the earlier system on Thursday.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Day 2...

A warm front extending eastward from a significant low pressure
across the Great Lakes will result in expanding precipitation
Saturday night into Sunday. Although the low itself will track well
northwest of the region, impressive warm/moist advection surging
northward from the Gulf will spread PW anomalies to as much as +3
sigma on an 850mb LLJ reaching as high as 50 kts. As this occurs, a
Canadian high pressure initially placed just north of the region
will rapidly retreat to the northeast, allowing the warm air to
flood unimpeded northward, lifting a warm nose above 0C all the way
into Canada. This suggests that precipitation will begin as a
period of snow across northern Maine, but will otherwise be a
combination of sleet/freezing rain, especially in the higher
elevations, before transitioning to all rain by Sunday aftn.=20

Total accumulations of any individual wintry precipitation type
will likely be modest as the warm air overwhelms the column, but
impactful snow and ice is still likely. This is reflected by WPC
probabilities for 4+ inches of snow that reach 10-30% in far
northern ME (just Aroostook County), and WPC probabilities for ice
exceeding 0.1" reaching 10-30% in the higher terrain of northern NH
and interior/western ME.


Weiss


...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_RTUz_614JoHj-DnsYqKZMHb3ujwYTJa4xgb7BGgRWKI3= LpnUbvsVPDM6Qb8x-CpR28EkFUbkpt4uaL1tqIuH_W-mR0$=20



$$

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FOUS11 KWBC 040726
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 AM EDT Sat Apr 4 2026

Valid 12Z Sat Apr 04 2026 - 12Z Tue Apr 07 2026


...Northern Plains, Upper Midwest, & Western Great Lakes...
Day 1...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region today...

Significant late-season winter storm is ongoing this morning extending
from the Dakotas across the Midwest towards the MI U.P.. Moderate
to heavy snow occurring across the Dakotas is expected to diminish
by midday as snowfall continues across central and northern MN=20
through this evening. Meanwhile, to the north and northeast of the=20 associated low pressure system, freezing rain will be the primary=20
winter precipitation type throughout northern WI and both the U.P.=20
and northern L.P. of MI. This significant low will track northeast=20
from the Midwest through the Great Lakes by this evening and=20
quickly exit into southeast Canada tonight while hazardous winter=20 precipitation concludes as well.=20

As this low pressure system and accompanying upper low track E/NE=20
today, continuing downstream moisture advection will peak later
this morning leading to impressive isentropic ascent, especially=20
along the 290-295K surfaces, lifting into the Upper Midwest. Mixing
ratios within these layers of 3-5 g/kg reflect the anomalous=20
moisture being wrapped into the system, and it is likely that=20
precipitation will become even more widespread by sunrise this
morning. At the same time, the accompanying theta-e ridge will=20
wrap cyclonically around the system and lift into a TROWAL, while=20
the impressive upper low forces intense deformation to drive=20
tremendous ascent into the TROWAL. The combination of the deep=20
layer ascent with robust mesoscale forcing will result in banded=20
structures with snowfall rates for which the 00z HREF suggests=20
will reach 1-2"/hr at times, especially from eastern ND into=20
northern MN where some pivoting of these bands may also occur. This
will result in heavy total snowfall accumulations around one foot.
However, just outside of these pivoting heavier bands and within
lighter snow rates, totals will likely be limited by the early=20
April sun- angle combined with surface temperatures in the low-30s.
WPC probabilities start at 12Z today (heavy snow is ongoing before
12Z as well) and indicate a 50-80% chance of at least 8 inches of=20
additional snow in northern/northeastern MN today.

Farther southeast, the strong WAA east of the upper low and a warm
nose pushing northward is leading to an area of heavy mixed=20
precipitation including sleet and freezing rain. Even with a deep
cold layer and period of sleet, warm nose energy rapidly increases
this morning leading to a changeover to an extended period of=20
freezing rain before the dry slot pushes northward (likely=20
preventing a changeover to rain in some areas) this afternoon.=20
While sleet accumulations on both shores of Lake Superior may reach
0.5", the more significant hazard is expected to be freezing rain=20
where the latest WSSI depicts widespread Moderate Impacts
associated with freezing rain from northern WI to the eastern=20
U.P.. This icing could be damaging where totals exceed a quarter=20
inch, causing power outages and tree damage, and will likely=20
exacerbate and prolong impacts ongoing from the ice/snow which=20
occurred with the earlier system on Thursday.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Days 1-2...

A warm front extending eastward from a significant low pressure
across the Great Lakes will result in expanding precipitation
tonight into Sunday. Although the low itself will track well=20
northwest of the region, impressive warm/moist advection surging=20
northward from the Gulf will spread PW anomalies to as much as +3=20
sigma on an 850mb LLJ reaching as high as 50 kts. As this occurs, a
Canadian high pressure initially placed just north of the region=20
will rapidly retreat to the northeast, allowing the warm air to=20
flood unimpeded northward, lifting a warm nose above 0C all the way
into Canada. This suggests that precipitation will begin as a=20
period of snow across northern Maine, but will otherwise be a=20
combination of sleet/freezing rain, especially in the higher=20
elevations, before transitioning to all rain by Sunday aftn.=20

Total accumulations of any individual wintry precipitation type
will likely be modest as the warm air overwhelms the column, but
impactful ice is most likely. This is reflected by WPC=20
probabilities for ice exceeding 0.1" reaching 30-60% in the higher
terrain of northern NH and interior/western ME.


Snell/Weiss



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!7-wqkXAXEAhei98H4zGUIqbrdkbPBibX_Ay6RBKrVIlnI= 6QA8n9Z7a38ZGGBam9_UiMOV-uhVff4GqNeA51OBIyDIEY$=20



$$

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FOUS11 KWBC 041803
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
203 PM EDT Sat Apr 4 2026

Valid 00Z Sun Apr 05 2026 - 00Z Wed Apr 08 2026


...Northern Plains, Upper Midwest, & Western Great Lakes...
Day 1...

...Significant winter storm ongoing today will wind down this=20
evening...

The significant winter storm which has produced over a foot of snow
in parts of the Dakotas and more than 1/4 inch of ice in Wisconsin
will continue today, but wane quickly after 00Z, with all wintry=20 precipitation coming to an end by 12Z Sunday. Snowfall lingering=20
across northern MN after 00Z will generally be underneath the=20
remnant pivoting deformation band as it crosses more firmly into=20
Canada, with some light snow developing on lake enhancement into=20
the western U.P. of MI overnight as well. Snowfall rates within any
of these snow areas are expected to be modest as the most=20
significant forcing pulls away to the east, leading to just=20
additional light snowfall accumulations of just 2-4", highest in=20
the western U.P. Despite this modest additional accumulation,=20
impacts from this storm will linger through the weekend after this=20
heavy snow and significant icing, which only compounded impacts=20
from Thursday's system.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Day 1...

Precipitation will spread across northern New England tonight and
continue through Sunday afternoon as a warm front extending from a
significant system in the Great Lakes moves into the region.
Moisture will spread northward from the Gulf and ascent
isentropically atop the warm front, expanding the precipitation
shield but also driving a warm nose >0C northward as Canadian high
pressure retreats. The timing of the heaviest wintry precipitation
is likely between 06Z/Sunday to 18Z/Sunday, during which time a
mixture of snow, sleet, and freezing rain will occur before
transitioning to all rain. Total accumulations of any wintry
precipitation are expected to be modest, but still produce impacts
to travel as reflected by 20-40% chance for moderate impacts in the
WSSI-P, focused over the higher terrain of NH and ME. WPC
probabilities for snow exceeding 4" are just around 10% across
northern Aroostook County, ME. Freezing rain is likely to be more
widespread as at least a glaze of ice is possible for the higher
terrain of the Adirondacks and all of central/northern New England.
However, significant icing exceeding 0.1" is expected to be
confined to just the higher terrain of NH and ME where WPC
probabilities are 30-50%.


...Great Lakes...
Day 2...

A fast moving and compact shortwave diving out of Manitoba will
race southeast and cross the western Great Lakes Monday before
becoming embedded in the broad cyclonic flow across the Northeast.
This shortwave will help develop a weak wave of low pressure along
an inverted surface trough tracking southeast across Michigan
Monday. Any warm advection snowfall may stay just north of the
region, but sufficient cold advection behind this wave will drop
850mb temps down to below -15C, sufficient for late season lake
effect snow (LES) as lapse rates steepen atop the slowly warming
Great Lakes. Heavy snow is likely to develop within this CAA south
of Lake Superior, especially along the western U.P. of MI where WPC probabilities for 4+ inches are 50-70%.


Weiss


...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_5iLgzzq9ZNwfJR9f8Tf9B1M8oC-MmIbhqhf9hy6VB333= RCV4NLi3YBaTrVOvyR8ffPg2dN_TGg35yrK7tVfADs4Kcg$=20



$$

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FOUS11 KWBC 051814
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
214 PM EDT Sun Apr 5 2026

Valid 00Z Mon Apr 06 2026 - 00Z Thu Apr 09 2026


...Great Lakes & Northeast...
Days 1-2...

Compact shortwave digging out of Manitoba will race southeast,
crossing the Upper Midwest and Great Lakes Monday before becoming
embedded into the more synoptic cyclonic flow across the Northeast
by Tuesday. This will help spawn a weak wave of low pressure along
an inverted surface trough, with locally enhanced moist advection
in the vicinity of this low leading to a swath of light to moderate
snowfall. The heaviest synoptic snow should be generally north of
the international border, but CAA in the wake of this impulse will
push 850mb temps down to around -15C, producing a favorable
environment for lake effect snow (LES) in the favored NW snow belts
downstream of the Great Lakes. The duration and intensity of this
LES may be somewhat modest, but significant accumulations exceeding
4" are still possible (30-70% chance) across the western U.P. on
D1, and 10-50% along the Chautauqua Ridge east of Lake Erie on D2. Additionally, although accumulations are expected to be generally
less than 2", post impulse NW flow will create some upslope
snowfall across the Adirondacks and Greens on D2.


...Missouri Valley/Corn Belt...
Day 2...

An interesting evolution Monday night into Tuesday morning could
result in a very narrow corridor of heavy snowfall from eastern
Nebraska into Iowa and Missouri. A modest shortwave dropping across
the Central Rockies will cause weak height falls and broad
divergence across the region Monday night into Tuesday. At the same
time, a potent NW to SE oriented jet streak will arc southward on
the upwind side of a trough moving over the Great Lakes/Northeast,
leaving favorable RRQ diffluence overlapping the best mid-level
divergence. This mid- level pattern will push a cold front through
the region Monday, but it is likely that this front will begin to
kink and return northward with warm advection Tuesday morning as
850mb flow returns to the S/SW creating a narrow corridor of
impressive fgen as moist isentropic upglide ascends the boundary.

The overlap of this moist isentropic ascent with the RRQ of the jet
streak aloft will create a narrow stripe of intense 850-600mb fgen,
creating a streak of heavy precipitation. With the most intense
ascent expected to lift into the deepening DGZ (50% chance of at
least 50mb of DGZ depth according to the SREF), dynamic cooling
should overcome the generally marginal thermal structure, leading
to a stripe of heavy snow with snowfall rates potentially reaching
1"/hr. There remains considerable uncertainty into the placement
of this band due to its narrow nature, as well as the intensity of
any of the snow, but WPC probabilities have increased, and now
feature a 30-50% chance of at least 2" Tuesday morning, potentially
leading to a hazardous morning commute.


Weiss


$$

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FOUS11 KWBC 060710
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
310 AM EDT Mon Apr 6 2026

Valid 12Z Mon Apr 06 2026 - 12Z Thu Apr 09 2026


...Missouri Valley/Corn Belt...
Day 1...

An interesting evolution during the second half of Day 1 (00Z -
12Z Tuesday) could result in a very narrow corridor of heavy
snowfall from eastern Nebraska into southwest Iowa and far
northern Missouri. A modest shortwave dropping across the Central
Rockies will cause weak height falls and broad divergence across
the region Monday night into Tuesday morning. At the same time, a
potent NW to SE oriented jet streak will arc southward on the
upwind side of a trough moving over the Great Lakes/Northeast,
leaving favorable RRQ diffluence overlapping the best mid-level
divergence. This mid- level pattern will push a cold front through
the region today, but it is likely that this front will begin to
kink and return northward with warm advection Tuesday morning as
850mb flow returns to the S/SW creating a narrow corridor of
impressive fgen as moist isentropic upglide ascends the boundary.

The overlap of this moist isentropic ascent with the RRQ of the jet
streak aloft will create a narrow stripe of intense 850-600mb fgen,
creating a streak of heavy precipitation. With the most intense
ascent expected to lift into the deepening DGZ (50% chance of at
least 50mb of DGZ depth according to the SREF), dynamic cooling
should overcome the generally marginal thermal structure during the
overnight hours and absent of the April sun-angle, leading to a
stripe of heavy snow with snowfall rates potentially reaching
1"/hr. There remains some uncertainty into the placement of this
band due to its very narrow nature, as well as the intensity of
any of the snow. WPC probabilities have increased, and now feature
a 30-60% chance of at least 4" by Tuesday morning from east-
central NE through southwest IA, potentially leading to a hazardous
morning commute.


...Great Lakes & Northeast...
Days 1-2...

Compact shortwave digging out of Manitoba will race southeast,
crossing the Upper Midwest and Great Lakes today before becoming
embedded into the more synoptic cyclonic flow across the Northeast
by Tuesday. This will help spawn a weak wave of low pressure along
an inverted surface trough, with locally enhanced moist advection
in the vicinity of this low leading to a swath of light to moderate
snowfall. The heaviest synoptic snow should be generally north of
the international border, but CAA in the wake of this impulse will
push 850mb temps down to around -15C, producing a favorable
environment for lake effect snow (LES) in the favored NW snow belts
downstream of the Great Lakes. The duration and intensity of this
LES may be somewhat modest, but significant accumulations exceeding
4" are still possible (30-70% chance) across the Huron Mts of the
MI U.P. on D1, and 10-20% along the Chautauqua Ridge east of Lake
Erie on D2 on north through the favored upslope regions of the
Adirondacks and Green Mts.


Snell/Weiss


$$

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FOUS11 KWBC 061750
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
150 PM EDT Mon Apr 6 2026

Valid 12Z Mon Apr 06 2026 - 12Z Thu Apr 09 2026


...Missouri Valley/Corn Belt...
Day 1...

The guidance continues to suggest that a hyper-localized by intense
band of snowfall will develop from eastern NE through southern IA
and potentially as far as northern MO tonight and persist into late
Tuesday morning. Snowfall rates within this band will likely
eclipse 1"/hr at times (80% chance from the WPC prototype snowband
tool), and as this band translates slowly E/NE. This will create
significant snow accumulations, but with a very narrow footprint,
and difficult commuting Tuesday morning.

This band is expected to develop as a weak shortwave emerges from
the Central Rockies and advects E/SE creating subtle height falls
and mid-level divergence across the area. At the same time, a
potent jet streak around 130kts will pivot eastward over the Upper
Midwest, leaving its distant RRQ over the Corn Belt. The overlap of
the best divergence and upper diffluence will occur over NE/IA,
coincident with the placement of strongest 850mb warm/moist
advection as southerly return flow emerges from the Gulf. The
concurrent surge of the accompanying theta-e ridge will drive
sufficient moisture northward, and although PWs are expected to be
near normal, there is a narrow corridor of specific humidity in the
700-500mb layer which is progged to exceed the 90th percentile
according to NAEFS. This is a perfect overlap with the strongest
fgen (within the 700-500mb layer) suggesting that a narrow band of
heavy precipitation is likely, with snow likely the primary p-type
as ascent crosses the deepening DGZ.

Surface temperatures will be around to slightly above 0C, but the
rest of the column will be sub-freezing so as soon as intensity
ramps up (which will be quickly tonight) precipitation will change
to heavy snow, with the aforementioned 1"/hr+ rates becoming
dominant within this narrow plume. As the band pivots slowly
northeast, it will lead to rapid accumulations, and the high-res
guidance is beginning to focus from eastern NE through SW IA as the
area of most intense snowfall, and many of the deterministic models
suggest 6+ inches of snow, which is aligned with the NBMv5.0 PMM.
Since most of this snow will occur overnight into the morning
hours, melting loss due to the sun is not expected to be an issue,
so while confidence in a narrow band of heavy snow with continuous
amounts over 6" remains modest, the threat for significant impacts
has increased, leading to a hazardous morning commute. WPC
probabilities have climbed dramatically with the increase in the
12Z guidance suite, and now reflect a 50-70% for at least 4 inches
from near Omaha, NE through south-central IA. Locally 6-10" of snow
is possible if this band can linger in any one area with the 1+"/hr
snowfall rates.


...Great Lakes & Northeast...
Days 1-2...

Strung out vorticity associated with a compact shortwave will swing
from the Great Lakes to the Northeast tonight and Tuesday. The
modest height falls and PVA will lead to a compact low pressure
developing along an inverted trough, and as this feature moves east
D2 it will bring periods of moderate to heavy snowfall. This event
will contain two primary mechanisms for heavy snow.

The first will be along the inverted trough immediately ahead of
the wave of low pressure. In this area, the total snowfall is
expected to be minimal, but periods of convective snow showers are
expected as low-level convergence drives ascent into an airmass
with modest instability (SBCAPE 200-300 J/kg). With pockets of
low-level fgen additionally driving ascent, some areas, especially
across Upstate NY and central/southern New England could receive
multiple rounds of snow showers with briefly heavy snow rates,
gusty winds, and periodic visibility restrictions.

The more substantial snowfall accumulations are expected behind the
wave of low pressure as CAA develops to produce low-level fgen, and
NW flow drives substantial upslope enhancement into the Adirondacks
and Greens. The coverage and intensity of this snowfall is again
expected to be modest, but where upslope flow is most pronounced,
WPC probabilities suggest a 10-30% chance of 4+ inches of snow,
especially across the Adirondacks/Greens/Whites. Developing
deformation, although modest, overlapping this CAA could cause this
swath of snowfall to progress all the way to the Atlantic coast of Massachusetts with a corridor of heavy snow rates reaching the
Portland/Boston area Tuesday night, albeit with minimal
accumulations.


Weiss


$$

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FOUS11 KWBC 071810
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
210 PM EDT Tue Apr 7 2026

Valid 00Z Wed Apr 08 2026 - 00Z Sat Apr 11 2026


The probability of significant snow and ice across the CONUS is
less than 10 percent.


Miller


$$

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FOUS11 KWBC 081855
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
255 PM EDT Wed Apr 8 2026

Valid 00Z Thu Apr 09 2026 - 00Z Sun Apr 12 2026


...Sierra Nevada...
Day 3...

A closed upper level low off the coast of California will
break down into open wave as it comes ashore Friday night into
Saturday. Quick on its heels will be a stronger and more compact
closed low which is set to make landfall over northern California
Saturday night into Sunday. In tandem, these features will send
waves of impressive moisture inland, headlined by PW anomalies of
150 to 200 percent of normal. These surges of moisture will
interact with the higher terrain of the Sierra Nevada, leading to
periods of moderate to heavy snow beginning Day 3 (Friday night
into Saturday) and continuing into the weekend. Southwest flow
ahead of these systems will initially keep snow levels relatively
high (generally above 9000ft). However, as colder air works in from
the west and northwest, snow levels are expected to drop closer to
6000ft by Saturday evening, and perhaps as low as 4500ft by early
Sunday morning.

The latest WPC probabilities for >6" of snow have increased with
this forecast package, and are now up to 50-80% across a large
portion of the Sierra Nevada. Meanwhile, probabilities for >12" of
snow have also increased, now up to 20-50% across the higher peaks
of the Sierra. Travel across the higher mountain passes will
increasingly become a concern through the weekend as snow levels
lower, which is highlighted by 40-80% WSSI-P probabilities for
moderate impacts.


Miller


$$

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FOUS11 KWBC 080632
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
232 AM EDT Wed Apr 8 2026

Valid 12Z Wed Apr 08 2026 - 12Z Sat Apr 11 2026


...Sierra Nevada...
Day 3...

Precipitation returns to the West Coast late this week and early
this upcoming weekend as a closed upper low slowly approaches the
California coastline on Friday and interacts with a separate system
dropping southeast from the Gulf of Alaska late Friday night. Snow
levels are forecast to remain rather high through Saturday morning
above 8000ft and higher than many major passes. Current WPC
probabilities valid through the end of Day 3 are low (20-40%) for
at least 6 inches of snowfall across the Sierra Nevada and mostly
for remote locations with an elevation above 9500ft. However, snow
levels are expected to lower by the very end of the short range
forecast period (12Z Saturday) potentially down to around 7500ft
and should continue to lower somewhat throughout the weekend into
next week.


Snell


$$

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FOUS11 KWBC 090716
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
316 AM EDT Thu Apr 9 2026

Valid 12Z Thu Apr 09 2026 - 12Z Sun Apr 12 2026


...Sierra Nevada...
Days 2-3...

A robust closed low will drop SSEward from the Gulf of Alaska
tomorrow and move into NorCal Saturday night into Sunday. Ahead of
that system a lead upper low will weaken into an open wave tonight
over NorCal but will bring in some moisture to the region. But it
will be the second system that will be the primary driver for
snowfall over the Sierra from late Friday/early Saturday through
Sunday (beyond this forecast period). Though moisture/IVT anomalies
will be modestly high (90th-95th percentile), the slow-moving
upper low will allow for a longer sustained fetch into the Sierra.
Moderate to heavy snow is expected over the High Sierra at first,
then lowering through many passes as colder air filters in. Snow
levels at precip onset tonight will be above 9000ft but fall to
7500-8000ft Friday morning, 6000ft Saturday morning, and
4000-4500ft Sunday morning. The heaviest snow is expected Saturday
afternoon through the overnight hours with rates of 1-3"/hr.

WPC probabilities for >6" of snow are >50% above 5000ft or so and
for >12" are >50% above 6000-7000ft or so. Total snowfall could
exceed 2-3ft for the event in the higher peaks (>50% chance).
Travel across the higher mountain passes (including I-80) will
increasingly become a concern through the weekend as snow levels
lower. Minor to moderate impacts can be expected over the Sierra
per the WSSI, with isolated major impacts in the High Sierra.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


$$

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FOUS11 KWBC 091815
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
215 PM EDT Thu Apr 9 2026

Valid 00Z Fri Apr 10 2026 - 00Z Mon Apr 13 2026


...Sierra Nevada...
Days 2-3...

A lead upper low will weaken into an open wave tonight as it moves
inland over NorCal. Quick on its heels, a more robust closed low
will drop from the Gulf of Alaska on Friday and move into NorCal
Saturday night into Sunday. The lead wave will have some initial
moisture with it, but it will be the second, stronger system that
will be the primary driver for snowfall over the Sierra from late
Friday/early Saturday through Sunday. While moisture/IVT anomalies
will only be modestly high (90th-95th percentile), the slow-moving
nature of the upper low will allow for a longer sustained fetch
into the Sierra. Moderate to heavy snow is expected over the High
Sierra at first, then lowering through many passes as colder air
filters in. Snow levels at precip onset tonight will be above
9000ft but fall to 7500-8000ft Friday morning, 6000ft Saturday
morning, and 4000-4500ft Sunday morning. The heaviest snow is
expected Saturday afternoon through early Sunday morning with
rates of 1-3"/hr.

WPC probabilities for >8 of snow are >50% above 5000ft or so and
for >12" are >50% above 6000-7000ft or so. Total snowfall could
exceed 2-3ft for the event in the higher peaks (>50% chance).
Travel across the higher mountain passes (including I-80) will
increasingly become a concern through the weekend as snow levels
lower. Minor to moderate impacts can be expected over the Sierra
per the WSSI, with isolated major impacts in the High Sierra.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller





$$

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FOUS11 KWBC 100646
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
246 AM EDT Fri Apr 10 2026

Valid 12Z Fri Apr 10 2026 - 12Z Mon Apr 13 2026

...Sierra Nevada...
Days 1-3...

An upper low just offshore NorCal this morning will will weaken
into an open wave this afternoon as it moves inland into the Great
Basin. Moisture is already flowing into the region but temperatures
are mild and snow levels are quite high (>9000ft). Just upstream,
a more robust closed low will drop southward from the Gulf of
Alaska and move into NorCal Saturday night through Sunday and
slowly weaken into Monday. This second stronger system will be the
primary driver for snowfall over the Sierra starting tonight and
continuing through the weekend. While moisture/IVT anomalies will
be modestly high (90th-98th percentile), the slow-moving nature of
the upper low will allow for a longer sustained fetch into the
Sierra at a fairly favorable wind direction from the SW. Moderate
to heavy snow is expected over the High Sierra at first, then
lowering through many passes as colder air filters in. Snow levels
above 9000ft will fall to 7500-8000ft today, 6000ft Saturday
morning, and 4000-4500ft Sunday morning before rising a bit later
in the day into early Monday (5000-5500ft) as the upper low starts
to weaken. The heaviest snow is expected late Saturday afternoon in
northern areas through Sunday across the rest of the Sierra with
rates of 1-3"/hr per the hires CAMS and WPC snowband probability
tracker page.

WPC probabilities for >8" of snow are >50% above 5000-5500ft or so
and for >18" are >50% above 6000-7000ft or so. Total snowfall for
the event could reach 2ft in the higher peaks above 8000ft (>50%
chance) and 4ft in the High Sierra peaks. Travel across the higher
mountain passes (including I-80) will increasingly become a concern
through the weekend as snow levels lower. Moderate to Major level
impacts can be expected over the Sierra per the WSSI.

Snow will also expand across the Great Basin on Sunday with minor
accumulations for most areas. However, parts of southeastern OR,
northern NV, the central ID ranges, and the Wind River Range in WY
could see in excess of 8 inches of snow through 12Z Mon (40-70%
chance).

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


$$

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FOUS11 KWBC 101859
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Fri Apr 10 2026

Valid 00Z Sat Apr 11 2026 - 00Z Tue Apr 14 2026

...Sierra Nevada & Northern California...
Days 1-3...

An upper low opening up off the northern CA coast will weaken, but
be quickly replaced by an even more potent upper low diving south
from Alaska to take up residence in a similar position by 00Z
Sunday. This deeper low is then forecast to drop slowly E/SE to
come onshore the Bay Area by 00Z Monday, before opening into a
longwave positively tilted trough centered over the Great Basin by
the end of the forecast period.

Forcing for ascent will maximize downstream of this secondary upper
low as mid-level divergence and height falls overlap into central
and northern CA. This will be accompanied by the LFQ of a
sharpening subtropical jet streak rotating around the upper low,
and the overlap of these features is expected to drive considerable
synoptic lift across the region, with orographic enhancement likely
into the Sierra and northern CA terrain due to the onshore 700mb
flow. This lift will act upon a rapidly moistening column as IVT
surges onshore (90% chance for at least 250 kg/m/s) leading to PW
anomalies reaching +1 to +2 sigma across much of CA.

This will result in an area of expanding precipitation, especially
00Z/Sun to 12Z/Mon over CA, with some modest spillover and spread
of precipitation into the Rockies and Great Basin thereafter.
However, the heaviest precip is expected in the Sierra and northern
CA terrain, which are also the areas that will experience heavy
snowfall as they will be above the falling snow levels. As far as
snow levels, they are expected to begin around 6000-8000 ft, but
will fall quickly through Sunday and into Monday as the upper low
moves onshore, becoming as low as 4500 ft, but steep lapse rates
beneath the upper low may cause snow to accumulate below 4000 ft as
reflected by the NBM 10th percentile.

Heavy snow rates reaching 1-3"/hr as progged by the WPC prototype
snowband tool in the terrain combined with 24-36 hours of moderate
to heavy snow will result in significant accumulations that have a
high risk (>70% chance) of reaching at least 18", with locally 2-3
feet possible (30-70% chance), highest in the high Sierra. This
will create moderate to major (70% chance of major) impacts across
the Sierra including many of the important passes.

Lesser, but still significant snow may expand across the Great
Basin and into parts of the Northern Rockies, leading to pockets of
WPC probabilities exceeding 30% for 8+ inches in the highest
elevations of NV, southern OR, and parts of ID.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Weiss


$$

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FOUS11 KWBC 101900
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Fri Apr 10 2026

Valid 00Z Sat Apr 11 2026 - 00Z Tue Apr 14 2026

...Sierra Nevada through the Northern Rockies...
Days 1-3...

An upper low opening up off the northern CA coast will weaken, but
be quickly replaced by an even more potent upper low diving south
from Alaska to take up residence in a similar position by 00Z
Sunday. This deeper low is then forecast to drop slowly E/SE to
come onshore the Bay Area by 00Z Monday, before opening into a
longwave positively tilted trough centered over the Great Basin by
the end of the forecast period.

Forcing for ascent will maximize downstream of this secondary upper
low as mid-level divergence and height falls overlap into central
and northern CA. This will be accompanied by the LFQ of a
sharpening subtropical jet streak rotating around the upper low,
and the overlap of these features is expected to drive considerable
synoptic lift across the region, with orographic enhancement likely
into the Sierra and northern CA terrain due to the onshore 700mb
flow. This lift will act upon a rapidly moistening column as IVT
surges onshore (90% chance for at least 250 kg/m/s) leading to PW
anomalies reaching +1 to +2 sigma across much of CA.

This will result in an area of expanding precipitation, especially
00Z/Sun to 12Z/Mon over CA, with some modest spillover and spread
of precipitation into the Rockies and Great Basin thereafter.
However, the heaviest precip is expected in the Sierra and northern
CA terrain, which are also the areas that will experience heavy
snowfall as they will be above the falling snow levels. As far as
snow levels, they are expected to begin around 6000-8000 ft, but
will fall quickly through Sunday and into Monday as the upper low
moves onshore, becoming as low as 4500 ft, but steep lapse rates
beneath the upper low may cause snow to accumulate below 4000 ft as
reflected by the NBM 10th percentile.

Heavy snow rates reaching 1-3"/hr as progged by the WPC prototype
snowband tool in the terrain combined with 24-36 hours of moderate
to heavy snow will result in significant accumulations that have a
high risk (>70% chance) of reaching at least 18", with locally 2-3
feet possible (30-70% chance), highest in the high Sierra. This
will create moderate to major (70% chance of major) impacts across
the Sierra including many of the important passes.

Lesser, but still significant snow may expand across the Great
Basin and into parts of the Northern Rockies, leading to pockets of
WPC probabilities exceeding 30% for 8+ inches in the highest
elevations of NV, southern OR, and parts of ID.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Weiss





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FOUS11 KWBC 110623
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
223 AM EDT Sat Apr 11 2026

Valid 12Z Sat Apr 11 2026 - 12Z Tue Apr 14 2026

...Sierra Nevada and Rockies...
Days 1-3...

Light snow associated with a weakening upper trough moving east of
the northern Sierra will continue into the afternoon in advance of
a more potent upper low diving south from Alaska. This deeper low
will move into NorCal tonight before slowly opening into a longwave positively-tilted trough Monday around Reno and continuing into
Utah by early Tuesday morning.

Despite the overall weakening of the upper low through the period,
the combination of modest moisture anomalies (>90th-95th
percentiles for PW/IVT), incoming height falls, mid- level
divergence, an incoming 120kt jet streak, and upslope enhancement
via favorable mid-level flow will yield moderate to locally heavy
snow for tonight into Sunday over the Sierra.

The heaviest snowfall over the Sierra will be just in advance of
the upper/sfc low tonight through Sunday. Snow will also expand
eastward and northeastward across the Great Basin via broad SW flow
and PVA in the mid-levels. Snow levels will continue to fall today
into Sunday from around 6000-7000ft to around/below 4500ft with
the core of the colder air aloft. Snow rates of 1-3"/hr are likely
in the Sierra, making for difficult travel across the passes (WSSI
Moderate to Major impacts).

WPC probabilities of at least 8 inches of snow are >50% above
about 4500-5000ft in the Sierra and for at least 18 inches of snow
are >50% above about 5500-6000ft. Total accumulations may exceed
2-4ft in the highest peaks with windy conditions as well.

For the Great Basin to the Rockies, light to locally modest snow
in association with the incoming system will spread across the
region Sunday and continue through Monday. WPC probabilities for at
least 8 inches of snow are >50% above about 8000ft over eastern
NV/OR into the central Idaho ranges and above 10,000-11,000ft into
the Wind River Range and the Uintas.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso

$$

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FOUS11 KWBC 111752
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
152 PM EDT Sat Apr 11 2026

Valid 12Z Sat Apr 11 2026 - 12Z Tue Apr 14 2026

...Sierra Nevada and Rockies...
Days 1-3...

Anomalously deep low (500-700mb heights below the 0.5 percentile of
the CFSR climatology according to NAEFS) will spin onshore
California north of San Francisco by Sunday morning, and then
gradually weaken into an open trough as it progresses into the
Great Basin on Monday. Despite this steady weakening of the upper
feature, impressive ascent through height falls, PVA, divergence,
and upper jet streak, and strong orographic lift will create
widespread precipitation falling as snow in the higher elevations.
The heaviest snow is likely D1 across the Sierra when the WPC
prototype snowband tool indicates a high chance for 1-3"/hr
snowfall rates as snow levels fall to around 4500 ft beneath the
core of the upper low. This will create dangerous travel across
many of the Sierra Passes, with some of the northern California
passes (through the Shasta/Trinity region) also experiencing
hazardous travel due to heavy snow. WPC probabilities D1 are high

90%) for at least 12 inches of snow in the Sierra, with locally

2-3 feet possible before snow wanes quickly during D2. In the
Shasta/Trinity region, WPC probabilities D1 are moderate to high
for 12 inches.

Farther east into the Great Basin and the Rockies, light to
locally modest snow in association with the incoming system will
spread across the region Sunday and continue through Monday. WPC
probabilities for at least 6 inches of snow are >50% above about
8000ft over eastern NV/OR into the central Idaho ranges and above 10,000-11,000ft into the Wasatch and the Uintas.


...Washington...
Day 3...

Pinched mid-level flow south of a closed low dropping south along
the coast of British Columbia will combine with a zonally oriented
Pacific jet streak to drive moisture into Washington D3. This is
reflected by an IVT surge exceeding 300 kg/m/s according to the
West-WRF, with the core of this plume moving onshore Tuesday aftn
before steadily dropping southeast through 00Z/Wednesday. This
will manifest as increasing moisture and precipitation in a
relatively narrow corridor late D3 and continuing beyond this
forecast period. The overall column will be marginal for any wintry precipitation initially, but as the upper low approaches and a cold
front drops southward, snow levels will fall from 4000-5000 ft to
as low as 3000 ft by 00Z/Wednesday. This suggests most of the
significant accumulations will occur above many of the passes,
where WPC probabilities are 50-70% for at least 6 inches of snow,
but some light/slushy accumulations are possible as low as Stevens
and Snoqualmie Passes very late D3 and into D4 before snowfall
wanes on Wednesday.


...Colorado Rockies...
Day 3...

Closed mid-level low over the Great Basin Monday will open into a
positively tilted trough as it swings eastward, with an embedded
shortwave and vorticity maxima rotating through its base on
Tuesday. While there are considerable amplitude differences
through this evolution, the timing is generally well aligned among
the various ensemble camps, suggesting this shortwave/vorticity
maxima will move into the Central Rockies around 12Z Tuesday. The
corresponding ascent (through height falls and divergence) will
work in tandem with the LFQ of a poleward arcing jet streak to
drive lee cyclogenesis in eastern CO, with this low shifting
rapidly northeast into the Central Plains by the end of the
forecast period.

The mid-level SW flow will transport moisture into the area, while
increasing low-level southerly flow will tap some Gulf moisture as
well. However, the speed of this system ejecting northeast should
limit the ability of the accompanying theta-e to surge into CO, and
this is reflected by PWs that are progged to be around normal
according to NAEFS ensemble tables. Still, sufficient moisture
being wrung out by the impressive synoptic ascent will produce
areas of precipitation across the CO Rockies, with snow falling
above wavering snow levels between 6500-8000 ft. Total snowfall
will be somewhat modest, but WPC probabilities D3 indicate a 50-70%
chance of at least 4 inches across the San Juans and other higher
peaks of western CO.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Weiss


$$

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FOUS11 KWBC 120643
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
243 AM EDT Sun Apr 12 2026

Valid 12Z Sun Apr 12 2026 - 12Z Wed Apr 15 2026

...Sierra Nevada to the Rockies...
Days 1-3...

Deep upper low will move into NorCal today and continue to weaken
with its lead surface cold front already moving into/through the
Sierra. Despite this steady weakening of the upper feature,
impressive ascent through height falls, PVA, divergence, an upper
jet streak, and strong orographic lift will create widespread
precipitation falling as snow in the higher elevations. Though some
heavy snow has already fallen, additional modest to perhaps
heavier snow will continue in waves today over the Sierra with
1-2"/hr snowfall rates. Snow levels will fall to around 4500 ft
beneath the core of the upper low and create dangerous travel
across many of the Sierra Passes. WPC probabilities for at least an
additional 12 inches of snow are >50% above about 5000ft or so.

Farther east into the Great Basin and the Rockies, light to
locally modest snow in association with the incoming system will
spread across the region today and continue through Monday as broad
SW flow continues. By Tuesday, trailing vorticity on the SW side
of the weakening upper low this morning will move into the Four
Corners, enhancing snowfall over especially southwestern CO, but
more broadly over over the rest of the CO Rockies and also across
the Wasatch and Uintas. Snow levels initially around 8000-9000ft
will fall to around 7500ft by later Tuesday as most of the snow
ends from west to east. WPC probabilities for at least 6 inches of
snow are >50% above about 8000ft over eastern NV/OR into the
central Idaho ranges due to the lead upper trough today into
Monday, and above 10,000-11,000ft into the Wasatch, Uintas, and San
Juans.


...Pacific Northwest/Northern Rockies...
Day 3...

Troughing over Alaska today will steadily move southeastward along
the BC coast Tuesday, bringing a 105kt jet into western WA. A
modest surge of moisture along/ahead of the cold front (IVT values
around the 90th percentile for mid-April) will support widespread
rain and mountain snow starting around early Tuesday and continuing
into Wednesday. Snow levels initially around 3000ft (Cascades) to
4000ft (Northern Rockies) will fall to around 1500-2000ft in the
Cascades as much colder air works in from the northwest by 12Z
Wednesday (700mb temperatures dropping to around -10C to -14C) as
the cold front reaches the Cascades. This will bring snow to the
passes, though perhaps starting as rain in the lower passes, which
could be significant at higher passes. Through 12Z Wednesday, WPC
probabilities for at least 6 inches of snow are >50% above about
2500ft in the Cascades and 5000-6000ft in the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


$$

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FOUS11 KWBC 121806
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
206 PM EDT Sun Apr 12 2026

Valid 00Z Mon Apr 13 2026 - 00Z Thu Apr 16 2026

...Northern/Central Rockies...
Days 1-2...

An approaching upper trough and broad southwesterly flow will
allow light to moderate snow to spread across the Great Basin and
northern Rockies tonight through the day on Monday. By Tuesday,
trailing vorticity on the southwest side of this trough will move
into the Four Corners, enhancing snowfall more broadly over the CO
Rockies, including the Wasatch, Uintas, and especially the San
Juans in southwest CO. Snow levels initially around 8000-9000ft
will fall to around 7500ft by later Tuesday and early Wednesday as
most of the snow ends from west to east. WPC probabilities for at
least 6 inches of snow are >50% above about 8000ft over eastern OR
into the central ID ranges due to the lead upper trough into
Monday, and above 10,000-11,000ft into the Wasatch, Uintas, and San
Juans.


...Pacific Northwest/Northern Rockies...
Day 2-3...

Initial troughing over Alaska will steadily move southeastward
along the BC coast through Tuesday, bringing a 105kt jet into
western WA. A modest surge of moisture along/ahead of the cold
front (IVT values around the 90th percentile for mid-April) will
support widespread rain and mountain snow starting around early
Tuesday and continuing into Wednesday. Snow levels initially around
3000ft (Cascades) to 4000ft (Northern Rockies) will fall to around
1500-2000ft in the Cascades as much colder air works in from the
northwest by 12Z Wednesday and especially by 00Z Thursday (700mb
temperatures dropping to around -15C). Though precipitation may
start as rain, snow will quickly become the dominant p-type for
most passes. Some of this snow could even become significant at
higher passes, including Snoqualmie Pass and Washington Pass.
Through 00Z Thursday, WPC probabilities for at least 6 inches of
snow are >50% above about 2500ft in the Cascades and 5000-6000ft in
the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller





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FOUS11 KWBC 130711
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
311 AM EDT Mon Apr 13 2026

Valid 12Z Mon Apr 13 2026 - 12Z Thu Apr 16 2026

...Sierra to the Rockies...
Days 1-2...

Lead upper trough over the Great Basin will briefly close off and
continue northeastward then eastward, spreading snow over the
northern Great Basin into Idaho and Montana/Wyoming. Accumulations
will generally be light.Trailing vorticity on the southwest side of
the lead trough will close off into an upper low over SoCal this
morning and move eastward. This will bring another round of snow to
the central/southern Sierra this afternoon/evening with light to
modest accumulation of a few inches to perhaps 6-8 inches at the
highest peaks. Tonight into tomorrow, this upper low will move into
the Four Corners region, enhancing snowfall more broadly over the
Wasatch, Uintas, and especially the San Juans in southwest CO. Snow
levels initially around 8000-9000ft will fall to around 7500ft by
later Tuesday and early Wednesday as most of the snow ends from
west to east. WPC probabilities for at least 6 inches of snow are

50% above about 8000ft over eastern OR into the central ID ranges,

and above 10,000-11,000ft into the Wasatch, Uintas, and San Juans.


...Pacific Northwest/Northern Rockies...
Day 2-3...

Initial troughing over Alaska will steadily move southeastward
along the BC coast through Tuesday, bringing a 105kt jet into
western WA. A modest surge of moisture along/ahead of the cold
front (IVT values around the 90th percentile for mid-April) will
support widespread rain and mountain snow across the Cascades
starting around early Tuesday, becoming heavy Tuesday
afternoon/evening, and continuing as lighter snow into Wednesday.
Snow will spread eastward across the Northern Rockies Tuesday night
and into Wyoming by Wednesday. Snow levels initially around 3000ft
(Cascades) to 4000ft (Northern Rockies) will fall to around
1500-2000ft in the Cascades as much colder air works in from the
northwest by 12Z Wednesday and especially by 00Z Thursday (700mb
temperatures dropping to around -15C). Though precipitation may
start as rain, snow will quicklybecome the dominant p-type for most
passes. Some of this snow could even become significant at higher
passes, including Snoqualmie Pass and Washington Pass. By 12
Thursday, the upper trough will move inland, just past the
Cascades, ending snow from west to east just after the end of this
forecast period. Through 12Z Thursday, WPC probabilities for at
least 6 inches of snow are >50% above about 2500ft in the Cascades
and 5000-6000ft in the Northern Rockies. Probabilities for at least
a foot of snow are >50% above 3000-3500ft in the Cascades and
6000-7000ft in the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller



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FOUS11 KWBC 131838
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
238 PM EDT Mon Apr 13 2026

Valid 00Z Tue Apr 14 2026 - 00Z Fri Apr 17 2026

...Central Rockies...
Day 1...

Closed mid-level low emerging from the Great Basin will open into
an amplified, but positively tilted, trough as it ejects into the
Central Rockies by Tuesday evening. This will lead to a period of
enhanced lift through divergence and height falls, with the LFQ of
an accompanying upper jet streak helping to produce cyclogenesis in
the lee of the CO Rockies Tuesday aftn. Mid-level Pacific moisture
on the 700-500mb SW flow will increase column PWs to +1 to +2 sigma
across CO, with some additional low-level moisture becoming
available late D1 as cyclonic flow around the developing cyclone
creates E/NE winds from the Central Plains to advect additional
moisture westward from the Gulf moisture return. This moisture
being acted upon by the increased synoptic lift (and some upslope
flow on the low-level E/NE winds) will create periods of moderate
precipitation Tuesday, with significant snow accumulations expected
above generally 7000-8000 ft. WPC probabilities D1 are moderate to
high (50-90%) for 6+ inches across the Wasatch, San Juans, and CO
Rockies, with locally 12+ inches possible (30-50%) across the San
Juans before precip winds down very late Tuesday night as the
surface low pulls away to the east.


...Pacific Northwest through the Northern Rockies...
Days 1-3...

An increasingly active week of winter weather will begin today,
with widespread snowfall expected across most of the terrain from
the Pacific Northwest through the Northern Rockies.

The period begins with an amplified/closed low over southeast
Alaska dropping steadily southward to reach the British Columbia
coast by 00Z/Wed, and then pivot onshore WA/OR before 00Z/Thu. This
evolution will not only produce impressive height falls for ascent,
but also pinch the downstream flow to help surge Pacific moisture
into the region. This is reflected by IVT for which both the ECENS
and GEFS indicate has a >90% chance for exceeding 250 kg/m/s, with
the West-WRF indicating a narrow corridor of 500+ IVT surging
onshore as well. This IVT will be driven rapidly eastward beneath a
zonally oriented jet streak amplifying south of the upper low,
combined with intensifying SW low-level flow driving WAA ahead of a
surface cold front. Together, this will push PWs to +1-+2 sigma,
although the coverage of these highest PWs will be somewhat
confined to a narrow channel ahead of the cold front.

As this moisture spreads east and is acted upon by the robust
ascent, the result will be an expanding shield of precipitation,
with locally heavier precipitation expected in the higher terrain
where upslope enhancement is likely. Snow levels will vary widely
through the event, but are expected to generally fall D2/D3 behind
the cold front and the parent trough driving it southeast.

On D1, the heaviest accumulations are likely confined to the
Cascades as the event begins, which is reflected by WPC
probabilities for 6+ inches of snow above 50% focused in the WA
Cascades and Olympics, and generally above 4000 ft. During D2, the
coverage of heavy snow expands considerably as the front and
accompanying synoptic ascent shift east in tandem with the core of
the IVT moving inland. This results in WPC probabilities for 6+
inches being above 50% from the Olympics, along the WA and OR
Cascades, and eastward into the Blue Mountain, Sawtooth/Salmon
River, and much of the Northern Rockies. Snow levels in the Rockies
will fall from around 6000 ft to 4000 ft, but will crash well below
pass levels, as low as 2500 ft, in the Cascades, leading to
hazardous pass-travel. Finally, during D3 the snowfall will wane
across the Cascades but continue to expand eastward as far as the
Absarokas, Tetons, and Wind Rivers, while continuing across much
of the rest of the Northern Rockies. Snow levels D3 fall to
3000-4000 ft in these areas, with WPC probabilities suggesting a
70+% chance of at least another 6 inches of snow. Storm total
snowfall during this event will be considerable, forecast to reach
1-3 feet in the higher elevations.

Additionally, as the cold front sweeps southeast Wednesday night
and Thursday, it will be accompanied by a line of heavier
precipitation as low-level RH, 0-2km fgen, and 0-2km CAPE
maximize. The simulated reflectivity from the available guidance
suggests there will be a line of precip with embedded heavier
rates, and the snow squall parameter rises above 1. While the setup
is not ideal, and we are past the climatological favored period for
snow squalls, this setup does suggest the potential for convective
snow showers or snow squalls across the area. Additional snowfall
from any showers/squalls will be limited, but briefly heavy rates
and gusty winds could cause hazardous travel. This will need to be
monitored as we approach the high-res guidance windows to get a
better understanding of the timing, placement, and risk, of any
snow squalls.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.


Weiss


$$

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FOUS11 KWBC 140755
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
355 AM EDT Tue Apr 14 2026

Valid 12Z Tue Apr 14 2026 - 12Z Fri Apr 17 2026

...CO Rockies...
Day 1...

Upper low over southwestern UT this morning will move eastward and
weaken slightly into a strong trough as it enters the CO Rockies
this evening. SW flow will help bring in some moisture to the
region which will wring out light to moderate snow over the
Rockies. Snow levels will be around 7500-8000ft, so any significant accumulations of at least 6 inches are >50% above about 10,000ft.


...Pacific Northwest through the Northern Rockies...
Days 1-3...

Active wintry pattern from the Pacific Northwest through the
Northern Rockies starts today. A strong upper low moving
southeastward along the BC coast will dive into western WA tomorrow
evening and past the Divide Thursday evening. The upper low will
split into two pieces -- the northern portion will continue
eastward as a weakly closed upper low while the southern portion
will sink farther south into the Great Basin. Though moisture will
be rather limited (just a narrow surge of moisture ahead of the
cold front), heights and mid/lower-level temperatures will be well
below average and below the 1st percentile for this time of year,
reminiscent of a mid-winter system.

Rain and mountain snow will precede the cold front today with
initial snow levels around 3500-5000ft along the Cascades and
5000-6000ft over the Northern Rockies. Snow will increase later
this afternoon and tonight via upslope enhancement with rates of
1-3"/hr possible in the higher elevations, generally above the
passes. Cold front should push through the WA Cascades early
Wednesday which will push the heavier snow rates southward to stay
just ahead of the front into the OR Cascades. Snow levels will fall
to around 1000-1500ft tomorrow morning behind the front as snow
lightens. However, the upper low will then swing through with its
cold core and additional snow to around 1500-2000ft during the
afternoon hours. To the east, snow will increase over the Northern
Rockies where the cold front will take nearly a day longer to reach
past the Divide. There, too, snow levels will fall sharply behind
the front down to below 2000ft (i.e, all valley floors) where at
least some accumulation is probable. On Thursday
afternoon/overnight, the upper low will move through the Northern
Rockies with additional light to moderate snow mainly over SW MT
southward. Through 12Z Friday, with the strongest height falls over
northern UT into WY, snow will be favored over the northern
Wasatch/Unitas but especially into Wyoming (Bighorns) as it ends
over the Pacific Northwest.

WPC probabilities for at least 6 inches of snow are >50% above
about 2000-3000ft in the Cascades, 4000ft in the Northern Rockies,
and 7000ft in Wyoming. For at least a foot of snow, WPC
probabilities are >50% above about 3000-4000ft in the Cascades
(this includes Snoqualmie Pass), 5000-6500ft in the Northern
Rockies, and 9000-10,000ft in Wyoming. Total accumulations may
range from 1-3ft in the region, along with windy conditions, making
for very difficult to impossible travel through the terrain.

Additionally, the combination of the sharp cold front and well
below normal mid-level temperatures could yield some snow squalls
or at least some convective snow along/ahead of the front Thursday,
despite it being April (outside the more typical period). This
could cause short-lived but impactful drops in visibility and
hazardous travel.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


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FOUS11 KWBC 142027
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
427 PM EDT Tue Apr 14 2026

Valid 00Z Wed Apr 15 2026 - 00Z Sat Apr 18 2026


...Cascades...
Days 1-2...

A low pressure system currently centered over Southeast Alaska (aka
the Alaska Panhandle) will shift SE to central WA through Wednesday
before opening into a split trough with a portion that digs down
the Rockies through Friday and one that drifts east over the
southern Canadian Prairies. Pacific moisture is somewhat limited,
but the cold aspects of the system will make it reminiscent of a
mid-winter system.

Snow levels starting around 3500ft on the WA Cascades quickly drop
to 1000ft or less late this evening as the associated strong cold
front pushes through. The heavier snow rates will stay just ahead
of the front that works its way down the OR Cascades Wednesday. A
round of more moderate snow rates arrives to the WA Cascades with
the upper low center Wednesday afternoon. Snow levels bump up to
around 1500ft through this time before Cascades snow tapers off
Wednesday night.

Day 1 snow probs for >8" are 50-90% along the Cascades above about
2500ft including Snoqualmie and Santiam Passes. Winter Storm
Warnings remain in effect through the range. Day 2 snow probs for

4" are generally 30-50% for the central WA Cascades and

northern/central OR Cascades.


...North to Central Rockies and central High Plains...
Days 1-3...

Moisture shifts east across the Cascades through the northern
Rockies tonight through Wednesday before the plume settles over
northwest Wyoming Wednesday night into Thursday. The southern
portion of the trough drives expanding precip and a low level
upslope component to the CO Rockies and adjacent High Plains
Friday.

The cold front reaches northwest MT Wednesday morning with a
gradual progression to Wyoming through Wednesday night. Snow levels
ahead of the cold front are 5000-6000ft over MT before dropping to
2000-3000ft behind the front as rates decrease. Snow levels over WY
rise to 8000ft in the warm sector Wednesday before dropping to
3000ft Wednesday night behind the front. Snow levels around 9000ft
in CO on Thursday drop to 4000-5000ft through the day Friday.

Day 1.5 WPC snow probs for >8" are 40-80% for all western MT and central/northern ID ranges. Day 2 snow probs for >8" are 50-80% for
the Absarokas, Tetons, and the Wind River Range. Then Day 3 probs
for >6" are 40-80% for the Bighorns, Wind River again, and southern
WY through northern CO Ranges as well as the Uinta and higher
Wasatch in UT.

As a final note, the sharp cold front should produce snow squalls
or convective snow bands along/ahead of it Wednesday and Thursday.
This activity could cause short- lived but impactful drops in
visibility and hazardous travel.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.


Jackson



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FOUS11 KWBC 151905
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
305 PM EDT Wed Apr 15 2026

Valid 00Z Thu Apr 16 2026 - 00Z Sun Apr 19 2026


...Cascades...
Day 1...

Potent mid-level low drops over Washington State through this
evening with the leading cold front currently over OR pushing into
northern CA this afternoon. Instability showers in onshore flow
brings snow for the central WA Cascades south through the OR
Cascades into Thursday morning where Day 1 snow probs for >4" are
40-80% above the snow level that drops to around 1500ft through the
rest of this afternoon.


...North to Central Rockies and Central High Plains...
Days 1-2...

The mid-level low opens into a trough over the northern Rockies
early Thursday with a northern portion shifting east along the
Canadian border as a weakly closed low while the southern portion
digs through the Great Basin before turning east across the
central Rockies Friday. The preceding cold front provides a focus
for snow over central ID terrain this afternoon, shifting to
southern ID/western WY tonight. Snow levels of 6000-7000ft MSL
ahead of the front rapidly drop to 2000-3000ft (subterranean)
behind the front. Day 1 snow probs for >6" are 40-80% in central ID
(values reduced since the probs start at 00Z in ongoing snow) and
50-90% in terrain around greater Yellowstone including the Tetons
and Absarokas as well as the Wind River Range. The progression of
the front and southern lobe of the split trough through Thursday
night brings Day 1.5 snow probs for >6" to 60-90% for the Bighorns
and 40-70% for the Wasatch and Uinta.

The mid-level trough crosses CO on Friday providing much welcome
snow to western slopes of the northern/central CO Rockies. Day 2
snow probs for >6" are 40-70% for the Park and Front Ranges.
Northerly post-frontal flow brings a light snow risk to the Denver
metro Friday afternoon where Day 2 snow probs for >2" are 10-20%
for the northern side of the Palmer Divide into the foothills west
of Denver.

An additional note, the sharp cold front should produce
convective snow bands over eastern OR/central ID this afternoon and
southern UT into central WY Thursday afternoon. These may be strong
enough to qualify as snow squalls and cause hazardous drops in
visibility and flash freeze conditions on roads.


...Northern Plains...
Day 2...

The strong cold front associated with the low moving over the
Pacific Northwest this afternoon will push onto the northern Plains
Thursday. As the upper trough splits and digs down the Great Basin
Thursday night, a tightening baroclinic zone with enhanced SW flow
overhead with moisture from the southern Plains/Gulf will allow
snow bands to set up first over the Black Hills/western SD Thursday
evening and over eastern ND/northwest MN late Thursday night into
Friday. Marginal thermals look to be overcome in potent banding
from low level fgen forcing with moderate precip rates. 12Z
HRRR/3kmNAM in agreement for a subfreezing profile in the banding
with potential for a few inches of snow. Day 2 snow probs for >2"
are 40-60% from central to northeastern ND and the northwest corner
of MN. To the east of this snow swath is a risk for ice accretion
should the 2m temp remain below freezing. Day 2 ice probs for >0.1"
are 10-20% in northeast ND and across northwest MN.



Jackson



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FOUS11 KWBC 160756
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
356 AM EDT Thu Apr 16 2026

Valid 12Z Thu Apr 16 2026 - 12Z Sun Apr 19 2026


...North to Central Rockies and Central High Plains...
Days 1-2...

Shortwave trough moving across the interior Northwest will amplify
as it traverses into the Rockies, with 500-700mb heights falling
to between the 1st and 10th percentiles of the CFSR climatology.
This feature will remain generally progressive despite the
amplification, leading to broad but impressive ascent through
height falls/PVA combined with jet-level diffluence (with some
coupling noted over the Central Rockies leading to lee
cyclogenesis/surface low development.

Moisture will increase modestly, primarily in the 500-700mb layer
as streamlines suggest Pacific flow downstream of the primary
trough axis leading to elevated specific humidity in the mid-levels
despite TPWs remaining near-normal. Where the broad synoptic ascent
overlaps the greatest mid-level moisture, precipitation will
overspread the region, generally falling as light to moderate snow
above 6000 ft, at least initially. However, these snow levels will
fall to as low as 2000-3000 ft behind a sharp cold front which will
traverse E/SE beneath the primary trough, with upslope flow into
terrain and steep lapse rates beneath this cold core leading to
enhanced ascent and locally even lower snow levels at times.

Since this system remains progressive, total snowfall will be
somewhat modest, but locally much heavier accumulations are likely,
especially in the WY/CO terrain where some easterly low-level flow
around the developing surface low will enhance moisture and ascent.
2-day WPC probabilities indicate the heaviest snowfall will occur
across the higher elevations from the Absarokas into the Wind
Rivers, Big Horns, Laramies, Park Range of CO, and Front Range. In
these areas, the probability of at least 8 inches of snow is
between 50-90%, with locally more than 12 inches possible (30-50%)
across the Big Horns. Lighter snows (up to 4") are likely into the
High Plains of WY and CO, including along the Palmer Divide.

Additionally, snow squalls continue to appear possible along the
cold front, especially across parts of NV, UT, and WY today. While
snow accumulations from any squalls will be minimal, briefly heavy
snow rates and gusty winds could create dangerous travel.


...Northern Plains...
Days 1-2...

The strong cold front moving through the Central Rockies and High
Plains Thursday into Friday will continue eastward, reaching the
Northern Plains by Friday morning. Behind this front, the upper
trough will split, with a closed northern stream impulse moving
along the ND/Canada border on Friday, while secondary jet energy
lifts into the Upper Mississippi Valley to help drive ascent. The
overlap of the low-level baroclinic zone and this jet evolution
will result in impressive mid-level fgen acting upon a modestly
moistening column to produce a stripe of heavy precipitation.
Forecast profiles indicate that the low-level thermal structure
will be marginally favorable for snow, but the strong ascent into
(or just above) the DGZ will help dynamically cool the column to
result periods of heavy snowfall rates which could reach 1-2"/hr
at times as reflected by the WPC prototype snowband tool. With most
of this occurring before daybreak Friday, the snow could
accumulate efficiently during p-type changeover, and WPC
probabilities indicate a low risk (10-30% chance) of 4+ inches of
snow within this band, especially in parts of ND. Farther east,
some light mixed precipitation is also possible, reflected by WPC
probabilities that rise to 50-70% for at least 0.01" of ice for
parts of NW MN.


Weiss


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FOUS11 KWBC 161951
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
351 PM EDT Thu Apr 16 2026

Valid 00Z Fri Apr 17 2026 - 00Z Mon Apr 20 2026


...North and Central Rockies through the Northern Plains...
Day 1...

Mid-level trough axis over the northern Great Basin will dig
southeast to CO through Friday while a separate low over the
northern MT border will continue to track east to Winnipeg. Broad
ascent will persist ahead of these troughs which will enhance an
already tight baroclinic zone over the Dakotas tonight. Low level
moisture will continue to stream up the Plains tonight while
elevated Pacific moisture streams over the Rockies ahead of the
progressive cold front.

Some snow squalls/convective bands will continue to be possible
over UT/WY into this evening with the overall focus for snow on
terrain, shifting over CO through Friday.

Day 1 snow probs for >6" after 00Z are 40-60% in west-central MT
ranges, the highest areas around Yellowstone, around 70% on the
length of the Bighorns and 40-60% over southern WY/north and
central CO Ranges.

Jet energy east of the border low lifts over the Northern Plains
tonight which will overlap with the low-level baroclinic zone from
the front. Strong mid- level fgen acting upon a modestly
moistening column will produce a stripe of heavy banding from
western SD through central/eastern ND overnight. Snow becomes more
likely through the night with nocturnal trends and increasing
precip rates. A warm nose will also lead to some mixed precip near
the ND/MN border late tonight/early Friday. Day 1 snow probs for

4" are now 10-20% over central ND (a bit of a west shift from

overnight). Day 1 ice probs for >0.1" are 10-30% over northeast ND
through northwest MN.


Jackson


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FOUS11 KWBC 170709
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
309 AM EDT Fri Apr 17 2026

Valid 12Z Fri Apr 17 2026 - 12Z Mon Apr 20 2026


...North and Central Rockies through the Northern Plains...
Day 1...

De-ampifying shortwave trough will pivot E/NE across the Central
Rockies and Northern Plains through Saturday morning. Broad ascent
ahead of this trough (through a combination of height falls and
PVA) will interact with modest upper level diffluence within the
RRQ of a meridionally arcing, but weakening, jet streak. At the
surface, a cold front surging eastward will provide additional
ascent through convergence, with mid-level fgen in its wake
providing a focus for heavier precipitation as well.

Moisture will remain elevated through this evening thanks to a
combination of Pacific moisture streaming over the Rockies on broad
SW mid-level flow and southerly flow out of the Gulf lifting into
the Plains.

This will result in two axes of precipitation: lingering fgen mixed rain/snow/freezing rain in the Northern Plains, and continued light
to moderate snow across the Central Rockies. The heaviest snow and
ice in the Northern Plains is expected before 12Z, but residual
light freezing rain/snow through this aftn could result in light
accumulations of snow (less than 2 additional inches) and freezing
rain (less than 0.05 inches) from NW MN through the Arrowhead.
Farther south into the Central Rockies, especially in the higher
elevations of CO including the Park Range and Front Range, WPC
probabilities for 4+ inches of snow remain elevated at 50-70%
through D1 before precip shuts off tonight.


...Upstate New York/Northern New England...
Day 3...

A strong cold front will cross from Upstate NY Sunday morning to
well of the Atlantic Coast by Monday morning. A narrow corridor of
robust warm and moist advection ahead of this front will bring
periods of rain to New England, but as the the cold front races
east, temperatures will crash dramatically behind it. While this
front will also cause rapid drying of the column, there appears to
be enough of a residual SW flow in the mid-levels to allow for
anafrontal precipitation to continue, which will fall as snow in
the higher elevations of Upstate NY (in the Adirondacks) as well as
the Greens of VT, Whites of NH, and mountains of interior
western/northern ME. While snowfall accumulations should be
generally modest, a few inches of snowfall is possible as reflected
by WPC probabilities indicating a 10-30% chance of 4+ inches in
these higher elevation regions.


Weiss



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FOUS11 KWBC 171928
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
328 PM EDT Fri Apr 17 2026

Valid 00Z Sat Apr 18 2026 - 00Z Tue Apr 21 2026


...Colorado into Nebraska and Kansas...
Day 1...

Base of trough axis currently over the western CO Rockies will
shift to the High Plains through the rest of the afternoon. Height
falls above the post-frontal cold conditions will continue to
promote banded snow in the lee of the Front Range up into western
Neb and into western KS by this evening. Downsloping from the High
Plains east should cause snow to fall apart this evening.


...Upstate New York/Northern New England...
Days 2/3...

A strong cold front will push across the Northeast Sunday with an
upper trough lingering over the Northeast through Monday.
Northeastern Seaboard sfc low development on Sunday will promote
some lift behind the cold front which along with topographic lift
will bring some higher terrain snow accum in the Northeast
Sunday/Sunday night. Day 2.5 snow probs for >4" are limited to the
highest Adirondacks, Greens, and Whites.


Jackson



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FOUS11 KWBC 180559
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
159 AM EDT Sat Apr 18 2026

Valid 12Z Sat Apr 18 2026 - 12Z Tue Apr 21 2026


...Upstate New York/Northern New England...
Day 2...

A strong cold front driven by a potent vorticity streamer/shortwave
embedded within larger cyclonic flow centered over the Great Lakes
will race eastward across Upstate NY and New England early on
Sunday. The cold front likely outraces the accompanying mid-level
trough axis, which results in continued SW flow aloft, keeping
sufficient moisture present in the column as the low-level thermals
cool dramatically. This suggests that precipitation ahead of the
front, which will be rain, will rapidly transition to a period of
snow behind the front, especially in the higher elevations of the
Adirondacks, Greens, and Whites. The duration of snow after
changeover will be limited due to subsequent column drying, but NW
flow in the wake of this front will promote at least a period of
upslope enhancement to slow the drying enough for a few inches of
snow in these higher elevations. WPC probabilities have been
consistent the past few runs, and continue to suggest a 10-30%
chance for at least 4 inches of snow in the higher terrain from
northern Upstate NY through VT, NH, and western ME.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Weiss


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FOUS11 KWBC 181932
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
332 PM EDT Sat Apr 18 2026

Valid 00Z Sun Apr 19 2026 - 00Z Wed Apr 22 2026


...Upstate New York/Northern New England...
Days 1/2...

A strong cold front currently over Ohio shifts into western NY
tonight and crosses the Northeast Sunday. The associated mid-level
trough axis is over Lake Michigan and will cross Upstate NY Sunday.
Lift from the mid-level trough approach as well as sfc low pressure
development Sunday along the NJ to eastern New England coasts will
aid some precip on the cool side of the front with snow at higher
elevations in interior Northeast. Day 1.5 snow probs for >4" are
30-60% for the higher Adirondacks, Greens, Whites, and along the
NH/Maine border with Quebec. Included in this timeframe is
additional upslope snow in this terrain from NW flow in the wake
of the front Sunday night.


...California...
Day 3...

Low pressure developing well of the PacNW coast (around 135W)
deepens as it drifts SSE to off far northern CA through Monday. The
low then pivots east to northern CA through Tuesday. Decent
moisture arrives in a plume ahead of the low with snow levels
generally 6000-7000ft that then drop as low as 5500ft Tuesday under
height falls. Day 3 snow probs for >6" are 40-70% for the higher
Sierra nevada as well as Mt Lassen, Shasta, and the Trinity Alps.
Snow continues in earnest through Tuesday night as the low tracks
over the Sierra Nevada.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Jackson



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FOUS11 KWBC 190713
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
313 AM EDT Sun Apr 19 2026

Valid 12Z Sun Apr 19 2026 - 12Z Wed Apr 22 2026


...Upstate New York/Northern New England...
Day 1...

Strong cold front pressing east beneath increasing mid-level
cyclonic flow will cross New England Sunday morning with rapid
temperatures drops in its wake on impressive CAA. Moisture
streaming northward ahead of the front will fall as rain, but as
temperatures cool dramatically, precipitation will change to snow,
especially in the higher terrain of the Adirondacks, Greens,
Whites, and highest elevations of western/northern Maine before a
slow end as the column dries tonight. WPC probabilities remain
around 30-50% for 4+ inches of snow across the higher elevations
of this region.


...California...
Day 3...

Closed 500mb low will gradually translate east to come onshore
northern CA Tuesday aftn/eve. The guidance has been slowing with
this evolution over the past few model runs, but pronounced WAA
southeast of the core of this low will spread elevated IVT (>90%
chance of at least 250 kg/m/s and locally as high as 500 kg/m/s
according to the West-WRF) into CA late D2 into D3. This enhanced
IVT will moisten the column to result in widespread precipitation
as height falls and an accompanying Pacific jet streak move onshore
CA. Snow levels at precipitation onset will be 6000-7000 ft, but
should fall steadily beneath the upper low, becoming as low as 5000
ft by the end of the forecast period. However, steep lapse rates
beneath the upper low combined with strengthening ascent through
upslope flow, especially across the Sierra, may allow snow levels
to drop even further as reflected by NBM 10th% snow levels falling
below 4000 ft by 12Z Wednesday. While the heaviest accumulations
are expected to be above 5500 ft in the Sierra and Shasta/Trinity
region, some light accumulations are possible at these lower
elevations as well.

WPC probabilities for at least 8 inches of snow have climbed to
above 70% above 6000 ft in the Sierra and parts of the northern CA
terrain, and it is becoming likely that a warning-level snow event
will cause impact to travel across the Passes on Tuesday. After
coordination with the local WFOs, due to uncertainty in timing of
the event (as model trends have slowed) no hazards will be issued
yet, but it is likely in the next 1-2 model cycles winter storm
watches will be needed for the Sierra and possibly other
neighboring terrain as this event spreads northeast through mid-
week.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Weiss


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FOUS11 KWBC 192023
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
423 PM EDT Sun Apr 19 2026

Valid 00Z Mon Apr 20 2026 - 00Z Thu Apr 23 2026


...California...
Day 2 and 3...

A well defined upper low over the eastern Pacific will slowly make
its way towards northern California going into Tuesday, with a
plume of enhanced moisture ahead of it. This moisture axis should
reach the northern Sierra around 6Z Tuesday with snow levels
generally near 7000 feet ahead of the front, and then dropping to
below pass and lake levels by 00Z Wednesday as the core of the
upper low moves inland, and then closer to 5000 feet by 12Z
Wednesday as the low level lapse rates steepen, but the intensity
of the snow starts tapering off by then and becoming more in the
form of snow showers.

WPC probabilities for at least 12 inches have increased to greater
than 70% across the highest terrain of the central Sierra for the
24 hour period ending at 12Z Wednesday, and winter storm watches
have already been issued for this region. These same probabilities
are up to 30-40% for the Interstate 80 and Route 50 passes. Some of
the highest peaks/ridges in northern California are also likely to
get significant snow, but should not cause major impact on most
roads outside of the Sierra Nevada.

The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.

Hamrick/Jackson





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FOUS11 KWBC 200651
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
251 AM EDT Mon Apr 20 2026

Valid 12Z Mon Apr 20 2026 - 12Z Thu Apr 23 2026


...California...
Days 1-3...

Impressive upper low (500mb heights falling to the 2.5 percentile
level of the CFSR climatology) will approach the CA coast tonight
before swinging onshore Tuesday aftn. Although this feature is
likely to slowly decay with time D2 into D3, pronounced ascent
through height falls, PVA, and the LFQ of a jet streak pivoting
onshore downstream of the primary trough will help expand
precipitation across CA beginning this morning. The heaviest
precipitation is likely late Monday night through Tuesday evening
as the greatest IVT (50-60% chance of exceeding 500 kg/m/s from
both the ECENS and GEFS) pushes into CA within the confluent flow
southeast of the trough. While most of the precipitation will occur
as rain due to elevated snow levels, snow is likely in the highest
terrain of the Sierra and Shasta/Trinity region, especially Tuesday
as snow levels fall from around 6000-7000 ft down to as low as 4500
ft, potentially locally lower as steep lapse rates and
impressive ascent dynamically cool the column (the NBM 10th% snow
level drops to 3500 ft in the Sierra).

This will result in heavy snow accumulations, especially across the
Sierra, but also into the higher elevations of the northern CA
terrain as well. The most significant snowfall is likely today and
Tuesday before the strongest ascent lifts away to the northeast on
Wednesday, bringing an end to CA snow on D3. Before that occurs,
however, WPC probabilities indicate a high risk (>90%) for at least
12 inches of snow in the higher Sierra (above 6000 ft), with
lighter accumulations down to 4500 ft. Heavy snow is also likely in
the Shasta/Trinity region as reflected by WPC probabilities that
are above 70% for at least 8 inches. This will create hazardous
travel across the Sierra passes.


...Northern Rockies...
Day 3...

The same upper low which will bring heavy snow to California Monday
and Tuesday will continue its trek northeast on Wednesday as a
weakening, but still amplified, trough swinging into the Northern
Rockies. Although moisture will gradually decay (IVT less than 150
kg/m/s spilling into the Intermountain West) a strengthening
surface low across the Northern High Plains will work together with
continued mid-level SW flow (funneling the Pacific moisture) to
produce widespread precipitation across the region beginning
Wednesday morning. Sufficient synoptic ascent into this moistening
column will manifest as areas of heavy snow, initially only above
8000 ft, but then falling to around 5000 ft by the end of the
forecast period as the upper trough swings overhead. WPC
probabilities D3 suggest there is high risk (>70%) for widespread
light to moderate snowfall accumulations exceeding 4 inches from
the Blue Mountains of OR through the Sawtooth/Salmon River ranges
of ID, into the Absarokas, Little Belts, Tetons and other areas
around Yellowstone NP, and as far north as the Lewis Range around
Glacier NP. Locally, more than 8 inches is possible (30% chance)
near the Absarokas, Little Belts, and Tetons.

Although current model snowfall accumulations outside of the
higher terrain are modest, there is some concern that low-level
southerly flow downstream of the surface cyclone will pivot
cyclonically and lift the accompanying theta-e ridge into a TROWAL
across Montana D3. The new guidance is trending in this direction,
which could support some heavier snow banding across western parts
of the state. As of this time the probabilities for heavy snow
remain low, but this will need to be monitored for potentially
impactful snow dropping into lower elevations on Wednesday.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Weiss


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FOUS11 KWBC 201903
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
303 PM EDT Mon Apr 20 2026

Valid 00Z Tue Apr 21 2026 - 00Z Fri Apr 24 2026


...California...
Days 1-2...

GOES-West satellite imagery currently shows a large, closed, upper
level low slowly spinning over the eastern Pacific ocean off the
coast of CA. This anomalously deep upper low (500mb heights falling
to the 2.5 percentile level of the CFSR climatology) will
gradually inch closer to the CA coast tonight before swinging
inland Tuesday afternoon and evening as forward speed increases.
While the upper low is forecast to interact with incoming shortwave
energy dropping southward out of western Canada and then breakdown
into several smaller scale waves rotating around and within the
parent trough soon after making landfall, pronounced ascent through
height falls, PVA, and the LFQ of a jet streak pivoting onshore
downstream will help expand precipitation across CA tonight and
through the day on Tuesday. The heaviest precipitation is likely to
be focused during the daylight hours on Tuesday as a transient,
modestly strong atmospheric river (IVT nearing 500 kg/m/s and PW
anomalies over 200% of normal) pushes into CA within the confluent
flow southeast of the trough. Given marginal thermals and elevated
snow levels, most of the precipitation across CA is likely to fall
as rain. That being said, snow is likely in the highest terrain of
the Sierra and Shasta/Trinity region as snow levels fall from
around 6000-7000 ft down to as low as 4500 ft, potentially locally
lower as steep lapse rates and impressive ascent dynamically cool
the column (the NBM 10th% snow level drops to 3500 ft in the
Sierra).

Taking into account the combination of dynamic forcing, plume of
anomalous moisture, and lowering snow levels, heavy snow
accumulations are expected, especially across the Sierra, but also
into the higher elevations of the northern CA terrain as well. WPC probabilities indicate a high risk (>90%) for at least 12 inches of
snow in the higher Sierra (above 6000 ft), with lighter
accumulations down to 4500 ft. Heavy snow is also likely in the
Shasta/Trinity region as reflected by WPC probabilities that are
above 70% for at least 8 inches. With WSSI-P showing >90%
probabilities for moderate winter storm impacts and a 10-30% chance
of major impacts, travel across the Sierra passes will likely be
difficult at times through Wednesday. Snow intensity wanes during
the day on Wednesday before tapering off by Wednesday night.


...Northern Rockies...
Days 2-3...

The same system that will bring heavy snow to California will
continue its trek into the northern Rockies Wednesday into Thursday
as several pieces of shortwave energy pinwheel around and within a negatively-titled upper trough. Although moisture will gradually
decay (IVT less than 150 kg/m/s spilling into the Intermountain
West), a strengthening surface low across the northern High Plains
will work together with continued mid-level southwest flow
(funneling the Pacific moisture) to produce widespread
precipitation across the region beginning Wednesday morning.
Sufficient synoptic ascent into this moistening column will
manifest as areas of heavy snow, initially only above 8000 ft, but
then falling to around 5000 ft by the end of the forecast period as
the upper trough swings overhead. WPC probabilities show there is
a high risk (>70%) for widespread light to moderate snowfall
accumulations exceeding 4 inches from the Blue Mountains of OR
through the Sawtooth/Salmon River ranges of ID, into the Absarokas,
Little Belts, Tetons and other areas around Yellowstone NP, and as
far north as the Lewis Range around Glacier NP. Locally, more than
8 inches is possible (50% chance) near the Absarokas, Little
Belts, and Tetons.

Although current model snowfall accumulations outside of the
higher terrain are modest, there is at least some concern that low-
level southerly flow downstream of the surface cyclone will pivot
cyclonically and lift the accompanying theta-e ridge into a TROWAL
across Montana and the western Dakotas D3 into D4. As of this
time, the probabilities for heavy snow remain low, but this will
need to be monitored for potentially impactful accumulations
dropping into lower elevations Wednesday into Thursday.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Miller/Weiss





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FOUS11 KWBC 210630
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
230 AM EDT Tue Apr 21 2026

Valid 12Z Tue Apr 21 2026 - 12Z Fri Apr 24 2026


...California...
Days 1-2...

The heavily discussed and anticipated mid-level closed low
positioned off the CA/OR coast tonight will gradually lift E/NE,
with the core of the low progged to come onshore northern CA late
tonight/very early Wednesday morning. This evolution will result in
impressive height falls downstream into CA, with additional ascent
supplied by secondary shortwave energy rotating through this
trough and lifting northeast through the Great Basin. Impressive
height falls and PVA, working together with the LFQ of an upper
Pacific jet streak working onshore, will drive large scale ascent,
with lift becoming robust today and tonight.

This dep layer lift will act upon an increasingly moist column to
support widespread moderate to heavy precipitation. This moisture
will be channeled onshore via confluent flow E/SE of the upper low
and directly beneath the Pacific jet streak to drive IVT to around
500 kg/m/s as supported by the West-WRF and elevated probabilities
from the ECENS and GEFS (up to 60% chance). This steady stream
onshore of moisture will be wrung out by the aforementioned
synoptic lift, with additional ascent through upslope flow into the
terrain of northern CA and the Sierra providing locally enhanced
lift. ALthough snow levels will begin elevated at 6000-7000 ft,
they will crash rapidly beneath the upper trough, becoming as low
as 4500 ft, or even potentially lower (NBM 10th percentile is 3500
ft in the Sierra) due to steep lapse rates allowing for some precip-loading/dynamic cooling. This will result in heavy snow
accumulations in the terrain, especially above 6000 ft, but with
significant snowfall above 4500 ft also possible.

The heaviest snow is expected across the Sierra where D1 WPC
probabilities are high (>70%) for at least 12 inches of snow, and
1-2 feet is possible in the higher terrain. This will be in
response to snowfall rates that could reach 1-2+"/hr as reflected
by the WPC prototype snowband tool as the upslope flow into the
steep lapse rates aloft drives potential convective rates. With
this snow falling below many of the Sierra passes, treacherous to
impossible travel is likely (WSSI-P indicates a 40-50% chance of
major impacts due to heavy snow and wind). Farther north across the Shasta/Siskiyou/Trinity region, snow levels should generally remain
above the important travel passes, but in the higher elevations WPC probabilities are high (>70%) for at least 8 inches of
accumulation D1.

As the system ejects into the Great Basin and Northern Rockies D2,
the accompanying ascent will shift away from CA, bringing an end to
the heavy snow early Wednesday leaving only light/additional
accumulations across these areas.


...Northern Rockies...
Days 2-3...

The same system that will bring heavy snow to California will
continue its trek into the northern Rockies Wednesday into Thursday
as several pieces of shortwave energy pinwheel around and within a negatively-titled upper trough. Although moisture will gradually
decay (IVT less than 150 kg/m/s spilling into the Intermountain
West), a strengthening surface low across the northern High Plains
will work together with continued mid-level southwest flow
(funneling the Pacific moisture) to produce widespread
precipitation across the region beginning Wednesday morning.

Initially, snow levels are expected to be around 8000 ft, keeping
any significant accumulations confined to the highest elevations.
However, as the upper trough swings northeast, snow levels are
expected to fall steadily, becoming 4000-5000 ft by Thursday
morning, and falling even further to around 3000-4000 ft (possibly
as low as 2000 ft in the Northern High Plains) by the end of the
forecast period. While this still suggest that the heaviest
accumulations will occur in the higher elevations from the Blue
Mountains of OR through the Sawtooth/Salmon River area of ID and
into the Northern Rockies from near Glacier NP through Yellowstone
NP, some lower elevation accumulations are also becoming likely.

Confidence is high that heavy snow will accumulate in the terrain,
and this is reflected by 48-hr WPC probabilities (between 12Z Wed -
12Z Fri) that are high (>70%) for 8 inches in much of the higher
terrain between Glacier NP, Yellowstone NP, and west to the Blue
Mountains. Locally 18 inches of snow is possible (30% chance).

However, the most challenging aspect of this forecast involves what
happens on D3 as the surface low deepens across eastern MT and into
Canada. There continues to be diverging solutions of the various
global deterministic models with both the intensity of this low and
the accompanying upper level trough evolution. The GFS/GEFS
continue to look like the outlier/amplified scenario which is also
reflected in the D3/D4 clusters, but there has been a notable shift
to increase dispersion of the GEFS with more overlap from the
ECENS/CMCE from prior runs. However, 74% of the GEFS members still
make up the most amplified solutions, with nearly 1/2 of the GEFS
indicating the deepest trough and resulting heaviest snowfall into
the High Plains. While there is increasing confidence that
sufficient moisture lifting out of the Gulf will wrap into a TROWAL
and pivot SW around the low back into MT, the weaker solutions
supported by the ECENS/CMCE are still favored, especially noting
that the recent NAM has also trended away from the GEFS. Still,
there is potential for lower elevation snow from central to eastern
MT and eventually into ND, but at this time confidence is low in
any significant accumulations. It will need to be watched in
future model cycles however, for any potentially hazardous winter
weather outside of the terrain Wednesday into Thursday.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Weiss


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FOUS11 KWBC 211935
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
335 PM EDT Tue Apr 21 2026

Valid 00Z Wed Apr 22 2026 - 00Z Sat Apr 25 2026


...California...
Day 1...

The mid-level closed low currently off of the California/Oregon
coast will move inland tonight through early tomorrow morning.
Large-scale ascent, supported in part by left-exit region jet
dynamics, in combination with moist onshore flow, will contribute
to the continuation of heavy precipitation into the evening, with
snow rates of 1-2"/hr across parts of the Sierra Nevada. Snow
levels will drop through the evening and overnight to below 5,000
ft. However, precipitation rates are expected to diminish as the
low moves onshore, moisture advection decreases, and the better
forcing translates downstream. Across California, the bulk of the
additional precipitation is expected to occur before daybreak,
before entirely diminishing later in the day. An additional 6-12
inches of snow is likely for parts of the central Sierra Nevada,
especially for areas above 6,000 ft, this includes both the I-80
and U.S. 50 passes.


...Intermountain West to the Northern High Plains...
Days 1-3...

As the previously described system moves inland, snow will develop
initially over the higher elevations of Nevada and the eastern
Oregon mountains tonight, before reaching into the northern Rockies
by early tomorrow. Left-exit region upper jet forcing interacting
with residual moisture will help to focus some of the heavier
accumulations over the Oregon Blue Mountains tonight and then the
central to northern Idaho, western Montana, and western Wyoming
ranges beginning late tomorrow and continuing through Thursday.
Snow levels which are expected to start as high as 9,000+ ft around
the onset of precipitation are expected to fall steadily to
4,000-5,000 ft across most location by Thursday morning.

As periods of light to moderate snow continue farther west, strong
upward ascent afforded by a strong shortwave diving southeast out
of western Canada and upslope flow on the backside of its
associated low level cyclone will support the development of heavy
snow over the Big Horns. As the primary surface low deepens over
eastern Montana and moves into Canada, wrap around moisture will
spread across portions of eastern Montana and North Dakota on
Thursday. However, guidance suggests that warm boundary layer
conditions will limit snow accumulations. In contrast to previous
runs, the models have moved into better alignment with the
evolution of this system, with the GFS showing one of the bigger
adjustments from its previous run.

For many of the highlighted areas, probabilistic guidance indicates
that total accumulations of 8-12 inches will be common, especially
for areas above 6,000 ft.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.

Pereira

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FOUS11 KWBC 220635
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
235 AM EDT Wed Apr 22 2026

Valid 12Z Wed Apr 22 2026 - 12Z Sat Apr 25 2026


...Intermountain West to the Northern High Plains...
Days 1-3...

Large mid-level trough/gyre will lift northeast from the Great
Basin into the Northern Rockies while re-amplifying into a closed
low by Thursday morning. This large scale trough will bring
widespread synoptic ascent across the area, while secondary and
even tertiary shortwaves rotating around the larger system bring
additional ascent to locally maximize snowfall across the area.

While confidence is high in widespread snow, especially in the
higher terrain as snow levels begins around 7000-8000 ft before
falling steadily to 4000-5000 ft by Thursday, there is still
significant uncertainty into how the low elevations will fare. In
the higher terrain, especially D1 and D2 from the Blue Mountains of
Oregon through the Sawtooth/Salmon River ranges, east into the
Northern Rockies from near Glacier NP through Yellowstone NP
including the Lewis Range, Little/Big Belts, Absarokas, Tetons,
and Wind Rivers, WPC probabilities are high (>70%) for at least 8
inches of snow, with 1-2 feet possible (30-50%) in the highest
elevations of many of these ranges.

The challenge for this forecast then primarily involves around what
happens in the lower elevations, as well as how ascent responds to
overlapping secondary forcing as a cold front and shortwave dig
southward behind the primary surface low beneath the larger trough.
This may lead to two areas of heavier snowfall.

1) As the primary low deepens over far NE Montana, moisture
wrapping cyclonically around it (low-level flow emerging from the
Gulf) will lift into a TROWAL and pivot southwest back into MT. The
guidance has been insistent in this evolution, but still vary
widely in the intensity and position of this developing
deformation. Should this TROWAL become more intense, as reflected
by the GFS/NAM, but not as much in the ECMWF/CMC, a band of heavy
snowfall into the lower elevations is possible for central and
eastern MT. At this time that is not the likely scenario, but still
worth monitoring as the combination of dynamic cooling and heavy
snow rates could produce a few inches of snow in a short period of
time on Thursday.

2) The secondary shortwave digging out of Canada on the backside of
the larger trough will interact favorable with the low-level
baroclinicity (fgen) as the cold front sinks southward towards
northern WY. Impressive mesoscale ascent through the fgen/height
falls will overlap with intensifying upslope flow in the wake of
this front to create a swath of moderate to heavy snowfall from
Thursday night through Friday night in a relatively narrow
corridor from central ID through eastern WY. While some of this
heavy snow will occur atop areas that receive significant snowfall
from the first impulse, this secondary impulse could result in
snowfall reaching as low as 2500 ft according to the NBM. The exact
placement and intensity of this secondary corridor remains
uncertain as well, but where it does occur, WPC probabilities
indicate a moderate to high risk (50-90% chance) of at least 4
additional inches (or 4 new inches in lower elevations) with heavy
snow rates up to 1"/hr.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.


Weiss


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FOUS11 KWBC 221900
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Wed Apr 22 2026

Valid 00Z Thu Apr 23 2026 - 00Z Sun Apr 26 2026


...Northern Rockies to the High Plains...
Days 1-3...

As a deep mid-to-upper level low moves further inland over the
northwestern U.S., snow will continue to diminish over the
Cascades and Sierra Nevada while intensifying over portions of the
northern Rockies overnight. Left-exit region upper jet forcing
interacting with residual moisture will initially help to focus
some of the heavier accumulations along central to northern Idaho,
western Montana, and western Wyoming ranges. As the initial low
lifts north, a well-defined shortwave diving south from western
Canada will provide reinforcing ascent and a shot of colder air
across the northern Rockies beginning early tomorrow. Snow levels
are forecast to drop steadily over the northern and central Rockies
tomorrow into early Friday, dipping below 2,000 ft across northern
parts of the region. Light to moderate snow is expected to
continue into late Friday as the deep, vertically-stacked low
drifts into south-central Canada.

Probabilistic guidance indicates the heaviest snow totals will
focus from northern Idaho and western Montana to the western and
central Wyoming ranges. WPC probabilities indicate accumulations
exceeding inches will be likely, especially for areas above 6,000
ft, with some 18+ inch totals expected over parts of the higher
terrain. Some light accumulations -- less than 2 inches for most
locations -- are expected to spread out into the northeastern
Montana High Plains and east of the Big Horns to the Black Hills.


The probability for significant freezing rain exceeding 0.1 inches
across the CONUS is less than 10 percent.

Pereira

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FOUS11 KWBC 230706
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
306 AM EDT Thu Apr 23 2026

Valid 12Z Thu Apr 23 2026 - 12Z Sun Apr 26 2026


...Northern Rockies to the High Plains...
Days 1-2...

A 500mb vorticity maximum diving south from Alberta will interact
with a negatively-tilted disturbance over eastern MT to produce a
large and strengthening closed-low over south-central Canada
Thursday night. The 500mb pattern over North America by Friday
features a +PNA and -NAO regime that effectively weakens the 500mb
zonal flow over the continent and causes this closed low to remain quasi-stationary into the upcoming weekend. A steady stream of
700-300mb moisture on the western flank of the strengthening upper
low will be placed over the Northern Rockies while, at the same
time, surface high pressure over western Canada builds in. This
combination of easterly upslope flow via strengthening high
pressure to the north, along with a more than sufficient 850-700mb
CAA aloft will support periods of moderate-to-heavy snow over much
of the Northern Rockies, including ranges as far south as the
Tetons, Wind River, and Big Horns. The heaviest snow will reside
over the Bitterroots, Lewis Range, and Absaroka where upslope flow
and the core of the coldest temperatures aloft will reside the
longest with snow lasting through the day on Friday. Snow levels
will crash as low as 2,000ft in western MT and northern ID.

Perhaps the trickiest aspect of this forecast is the deformation
zone banding on the western and southwest flank of the develop
upper low this morning. Around 12Z, latest 00Z CAMs show the
atmospheric column cooling enough to support moderate-to-heavy snow
in northeast MT. After subsiding Thursday afternoon, 500mb
vorticity maxima revolving around the western flank of the closed
low looks to reinvigorate snow showers Thursday night and into
Friday morning. The NAM CIPS snow squall parameter shows a staunch
signal for snow squalls early Friday morning that could still
persist through the day given the unusually cold temperatures aloft
when combined with strong surface based heating during the day.
Snowfall totals are likely only to be around a coating to 2"in
these areas, but given north of the MT border, a narrow axis of >6"
snowfall totals is depicted in southern Saskatchewan. Any 50-100
mile shift south in the TROWAL axis over southern Canada could lead
to locally heavier amounts over northern MT that surpass 6".

WPC probabilities for this event show moderate-to-high chances
(50-80%) for snowfall totals >12" in the peaks of the Northern
Rockies above 6,000ft. Some hazardous travel impacts at pass level
are likely, although with NOHRSC showing many of these mountain
ranges with below normal snow depth for late April per NOHRSC, most
of the expected snowfall will be welcome. WPC probabilities also
snow a small portion of northeast MT with moderate-to-high chances
(50-80%) where snowfall totals >4" are depicted, suggesting some
members of the WPC super ensemble do in fact show the heavy snow
banding potentially protruding into northeast MT. The WSSI
generally shows Minor to locally Moderate Impacts in all of these aforementioned locations with Snow Amounts being the primary driver
in impact over the Northern Rockies. The WSSI suggest Blowing Snow
is the bigger potential impact from the Little Belt and Big Snowy
Mountains on east into the High Plains of northern MT.

...Sierra Nevada & Central Rockies...
Day 3...

A 500mb shortwave trough rotating around the southern flank of a
500mb low off the CA coast will track into the Southwest U.S. on
Saturday, bringing with it a slug of 700-300mb moisture.
Temperatures aloft are not overly cold, but healthy 500mb
vorticity advection coupled with the diffluent left-exit region of
a 250mb jet streak aloft supports vertical ascent. Plus, a 250-500
kg/m/s IVT over the Southwest supplies the Pacific moisture needed
to foster mountain snow. The lack of a very cold air-mass and the
progressive nature of this shortwave trough will keep snowfall
amounts more beneficial than harmful at a time where these mountain
ranges could use more snowpack. WPC probabilities show moderate-
to-high chances (50-70%) for snowfall totals >4" in southern
Sierra Nevada above 8,000ft and the more remote reaches of the
Wasatch, San Juans, Uinta, and central CO Rockies.

The probability for significant icing over one-tenth of an inch is
less than 10 percent.


Mullinax




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FOUS11 KWBC 231803
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
203 PM EDT Thu Apr 23 2026

Valid 00Z Fri Apr 24 2026 - 00Z Mon Apr 27 2026


...Northern Rockies onto the Northern High Plains...
Day 1...

A powerful low pressure system developing over southern
Saskatchewan today reaches peak intensity Friday morning as it
stalls and rapidly occludes. Precip associated with the low
continues over the Northern Rockies through Friday before tapering
off. Snow levels drop to ground level by this evening with SLR in
the 15:1 range for terrain. A reinforcing trough axis tracks across
eastern MT Friday which will provide focus for some snow
bands/potential squalls. The NAM CIPS snow squall parameter is
still robust across north-central/northeastern MT Friday 12Z to 03Z
Saturday.
Day 1 snow probs for >6" additional after 00Z are 40-70% for a
broad swath of ranges along the ID/MT border down through greater Yellowstone/Absaroka, Wind River, and 60-90% for the Bighorns. Day
1 probs for >4" are 40-60% for the Black Hills as well.


...Sierra Nevada to the South-Central Rockies...
Day 3...

A shortwave trough reaches the central CA coast Saturday as it's
drawn into a positively tilted trough axis over the northern
Rockies. The shortwave trough axis retains some autonomy as it
tracks over the CO Rockies on Sunday. Pacific moisture spreads in
ahead of the trough providing some much needed moisture for the
Intermountain West. Snow levels around 7000ft on the Sierra Nevada
at onset Saturday afternoon drop to around 6000ft Saturday night
before tapering off. Day 2.5 snow probs for >6" are 40-70% for the
higher central/southern Sierra Nevada.
Warm air advection over the Great Basin to the souther/central
Rockies brings some moderate precip rates and snow levels in the
8000 to 9000ft range. Day 3 snow probs for >6" are 40-80% for the
highest ranges in Utah (including the Uinta, Wasatch) and western
CO ranges including the San Juans and Elk as well as up to the Wind
River in Wyoming.


The probability for significant icing over one-tenth of an inch is
less than 10 percent.


Jackson



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FOUS11 KWBC 240721
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
321 AM EDT Fri Apr 24 2026

Valid 12Z Fri Apr 24 2026 - 12Z Mon Apr 27 2026


...Northern Rockies & Northern High Plains...
Day 1...

Cyclonic flow around the large closed upper-low will continue to
keep snow showers (and some snow squalls) in the forecast across
northern MT and far northwest ND today. Residual 700-300mb layer
moisture combined with easterly upslope flow will also support
additional mountain snow from the Bitterroots and Lewis Range on
south into the Absaroka, Tetons, Wind River, and Big Horn ranges.
Snow will gradually taper off this evening and remain light across
the Northern Rockies through early Saturday morning. WPC
probabilities show moderate-to-high chances (50-70%) for additional
snowfall totals >4" in the mountain rages of central MT, the Big
Horns, and the peaks of the WY Tetons. Additional light
accumulations of a coating-2" are likely along the MT/Canada
border. There are also low-to-moderate chanceS (20-40%) for
snowfall amounts >4" in the peaks of the Black Hills through Friday
night.


...Sierra Nevada to the Southern & Central Rockies...
Days 2-3...

A 500mb shortwave trough rotating around the southern flank of a
500mb low off the CA coast will track into the Southwest U.S. on
Saturday. Healthy PVA over the Rockies and the left-exit region of
a 250mb jet streak positioned overhead will foster excellent
upper-level divergence while a healthy slug of 700-300mb moisture
arrives from the subtropical Pacific. Temperatures aloft are not
overly cold, so snowfall will be confined to the higher elevations
of the Sierra Nevada on east across the Intermountain West. Snow levels
around 7000ft on the Sierra Nevada at onset Saturday afternoon drop
to around 6000ft Saturday night before tapering off.

48-hour WPC probabilities show moderate-to-high chances (50-80%)
for snowfall totals >8" in the Uinta and San Juans, with similar
odds for >4" of snow in the southern Sierra Nevada. Some of the
more remote peaks of the Sierra Nevada could see close to 10" of
snow, while the remote reaches of the Uinta and San Juans receive a
much-needed 12" of snowfall. Farther north, the Wind River, Tetons,
WY Absaroka, and Big Horns are likely to receive at least another
4" of snowfall on top of the snow they measured from the Thurs-Fri
storm system.


The probability for significant icing over one-tenth of an inch is
less than 10 percent.


Mullinax






$$

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FOUS11 KWBC 241818
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
218 PM EDT Fri Apr 24 2026

Valid 00Z Sat Apr 25 2026 - 00Z Tue Apr 28 2026


..Western U.S...
A 500mb shortwave trough rotating around the southern flank of a
500mb low off the CA coast will track across central California
Saturday night and reach the central Rockies by late Sunday.
Healthy PVA over the Rockies and the left-exit region of a 250mb
jet streak positioned overhead will foster excellent upper- level
divergence while a healthy slug of 700-300mb moisture arrives from
the subtropical Pacific. Temperatures aloft are not overly cold, so
snowfall will be confined to the higher elevations of the Sierra
Nevada on east across the Intermountain West.


...Sierra Nevada...
Day 2...

Precip onset Saturday afternoon for the central/southern Sierra
Nevada ahead of this wave where snow levels initially around
7500ft drop to around 6000ft Saturday night before precip tapers
off. Day 2 snow probs for >6" are 40-70% in the higher elevations
of the Sierra Nevada south of Sonora Pass and the White Mtns.


...Great Basin through central/southern Rockies...
Days 2/3...

Precip quickly expands from central NV through CO Saturday night
lingering through Sunday, then a secondary trough axis Monday
brings some more light precip to UT/CO. Snow levels linger around
8000ft in NV/UT while 9000ft snow levels in CO drop to 8000ft
Sunday evening. Day 2 snow probs for >6" are 50-60% on the highest
central NV ranges, Wasatch, Uinta, and southern Utah ranges. Day
2.5 snow probs for >6" are 50-90% in the San Juans/Elk ranges in CO
and 40-70% in the Park Range in CO and Wind River in WY. As of this
time the Monday snow is on the light side with Day 3.5 probs for

4" 40-60% in the Wasatch, Uinta and northern CO into southern WY

ranges.



The probability for significant icing over one-tenth of an inch is
less than 10 percent.


Jackson


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FOUS11 KWBC 250734
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
334 AM EDT Sat Apr 25 2026

Valid 12Z Sat Apr 25 2026 - 12Z Tue Apr 28 2026

...Western U.S Overview...

A 500mb shortwave trough rotating around the southern flank of a
500mb low off the CA coast today will track across central
California Saturday night and reach the central Rockies by late
Sunday. Healthy PVA over the Rockies and the left-exit region of a
250mb jet streak positioned overhead will foster excellent upper-
level divergence while a healthy slug of 700-300mb moisture arrives
from the subtropical Pacific. Temperatures aloft are not overly
cold, so snowfall will be confined to the higher elevations of the
Sierra Nevada on east across the Intermountain West. Meanwhile, a
secondary trough over the Pacific Northwest will generate the same
favorable divergence aloft on Sunday. This trough will become more
sheared Sunday night into Monday, but it will contribute to the
longwave trough entrenched over the West. These features will work
together to bring beneficial snowfall to the Rockies this weekend
and into Monday.


...Sierra Nevada...
Days 1-2...

Snowfall begins in the central/southern Sierra Nevada ahead of
this shortwave trough Saturday afternoon. Snow levels initially
around 7,500ft drop to around 6,000ft tonight before precip tapers
off. Some minor snowfall may linger on Sunday, but at the more
remote elevations above 9,000ft. Saturday and Sunday snow probs for

4" are >50% in the higher elevations of the Sierra Nevada south

of Sonora Pass and the White Mtns.


...Great Basin, central/southern Rockies, & the Black Hills...
Days 2-3...

Precipitation quickly expands east from central NV and into the CO
Rockies Saturday night lingering through Sunday. Snow levels
linger around 8000ft in NV/UT while 9,000ft snow levels in CO drop
to 8,000ft Sunday evening. The aforementioned secondary trough
axis delivers more light precip to UT/CO, while also expanding the precipitation shield farther north across western WY and the
southern MT Rockies on Sunday. The presence of the longwave trough
over the West will keep periods of lighto-to-moderate mountain snow
in the forecast through Monday. Days 2-3 snow probs for >4" are
high (>70%) for just about all of the mountain ranges referenced,
with the more remote reaches of the Uinta and CO Rockies having at
least 50% chances for over a foot of snowfall. Accumulating snow is
likely as far east as the Black Hills, where WPC probabilities
sport low-to-moderate chances (20-40%) for >4" of snowfall.

While some locally hazardous travel over nearby passes are
possible, snowfall throughout the Central Rockies will be more
beneficial than harmful, on account of the below average snowpack
throughout the region.


The probability for significant icing over one-tenth of an inch is
less than 10 percent.


Mullinax




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