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Excessive Rainfall Discussion...UPDATED
NWS Weather Prediction Center College Park MD
1129 PM EDT Sat Jun 28 2025

Day 1
Valid 0329Z Sun Jun 29 2025 - 12Z Mon Jun 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTH-CENTRAL MISSOURI/NORTH-CENTRAL ARKANSAS AS WELL AS PARTS OF
THE UPPER MIDWEST...

03Z Update...
Upgraded to a Slight Risk across portions of the Upper Midwest as
convection with intense rainfall rates has become increasingly
aligned with the 850 mb flow...leading to concerns about flash
flooding over portions of Minnesota into a small portion of far
eastern South Dakota for at least a few more hours. Furtber=20
details available in Mesoscale Precipitation 0546.

Bann


01Z Update...
Maintained outlooks in all four areas, with some adjustments based
on radar trends and recent hi-res guidance. The biggest adjustment
was to expand the Marginal Risk area over the southern High Plains
farther north and east to include ongoing convection along the
southeastern NM/northwestern TX border. Otherwise, made only minor
adjustments to the previous outlook areas, including the Slight
Risk centered over southern Missouri and northern Arkansas.

Pereira


Previous Discussion...

...Middle/Lower Mississippi Valley and adjacent southern
Plains, Ohio and Tennessee valleys...

Firmly in the warm sector and within a moist airmass containing
widespread PWATs of 1.8-2.2" (near the 90th climatological
percentile), isolated to scattered flash flooding is possible
today with a potentially higher focus across parts of southern MO
and northern AR tonight, where a Slight Risk of Excessive Rainfall
was introduced in the 16z update. An MCV evident on morning radar
and satellite imagery has already prompted a few FFWs across
eastern OK and KS while gradually pushing eastward. This feature
will aid in sparking widely scattered slow- moving thunderstorms
throughout the afternoon while instability levels rise due to
diurnal heating. Pulse thunderstorms within weak steering flow and
an unstable/moist environment are also likely through much of the
Ohio and Tennessee valleys today, with smaller scale scattered
flash flooding possible. Current trends are for the aforementioned
MCV to make it into the vicinity of southeast MO by late tonight
and influence a sharp mid-level trough ahead of increasing warm air
advection throughout the Plains due to a crossing shortwave in the
north- central U.S. and the nighttime low- level jet. CAMs still
differ somewhat in the exact location of a potential northwest-
southeast oriented band of slow-moving storms, but generally
converge on south-central MO and don't really develop until around
09z tonight. The 12z HREF has increased 24-hr probs (12z Sat-12z
Sun) for greater than 5" of rain to 30-45% within the Slight Risk
outline. Additionally, this part of the country also has relatively
saturated soils already (70-100% 0-40 cm below ground relative
soil moisture percentiles per NASA SPoRT) not including the
likelihood of scattered thunderstorms and potentially overlapping
heavy rainfall this afternoon.

...Northern Plains and Upper Midwest...

Showers and thunderstorms capable of producing locally heavy
rainfall rates and heavy rainfall totals have the potential to
produce flash flooding as the next upper shortwave trough
approaches the north-central United States. Aided by a 90kt upper
level jet streak on the lee side...the upper trough will generate a
compact area of fairly robust, transient deep-layer forcing over
the outlook area later today and tonight. MUCAPEs are expected to
soar within the warm sector prior to the surface cold frontal
passage late tonight. Given precipitable water values getting near
1.75 inches...storms which form within the unstable airmass will
be capable of producing rainfall rates in excess 1.5"/hr and areal
average rainfall amounts of 1 to 3 inches...especially once low-
level inflow accelerates to between 30 kts and 40kts at 850 mb
ahead of the approaching front. The storm/mesoscale nature of the
threat leads to uncertainty of a more focused corridor of higher
risk, but a Slight Risk was considered in central MN where forward
propagation of storms may begin slow this evening and is reinforced
by the highest 12z HREF probs (20-30%) for exceeding 3" in 6 hours.

...Central Appalachians to the Northeast...

There continues to be a concern for heavy to potentially excessive
rainfall to develop across western Pennsylvania and surrounding
areas as the frontal boundary sags southward and taps into the
pooled PW values of 1.5-2". 12z CAMs are not a robust with rainfall
amounts in the central Appalachians and keep things moving along in
the Northeast to limit any flash flooding to isolated instances.
However, the environment remains unstable and moist, so any slow-
moving storms could lead to forming mesoscale boundaries that
create locally intense rainfall. Farther north, the Marginal Risk
was removed across northern New England given unimpressive radar
trends this morning and a more progressive patter. Still, 1-1.5" of
rainfall could lead to very isolated and more nuisance flooding.

...Southeast and central Florida Peninsula...

Scattered pulse thunderstorms are expected across a broad warm
sector and near an upper trough lingering over the region as
seasonable instability develops with daytime heating. A greater
focus for intense rainfall also overlaps with higher FFG across
the central Gulf Coast and Florida Peninsula, where rainfall rates
of 2-3"/hr are possible but should weaken quickly before
convection is driven off outflow from numerous other pop-up storms.

...New Mexico...

Yet another day of thunderstorms is expected across portions of
southern New Mexico and west Texas with locally heavy rainfall
(1-2") possible. QPF trends (coverage, intensity) are more isolated
compared prior days with the moist south to southeast low-level
upslope flow likely resulting in more localized areas of heavier
rainfall focused across the Sacramento and Guadalupe Mtns south
through the Trans-Pecos. The flash flood potential is expected to
remain isolated.

Snell

Day 2
Valid 12Z Mon Jun 30 2025 - 12Z Tue Jul 01 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL EXTENDING FROM
PORTIONS OF THE CENTRAL UNITED STATES TO THE CENTRAL GULF COAST AND MID-ATLANTIC...

Late-June weather pattern remains in place on Sunday with widely
scattered showers/storms and isolated chances for flash flooding
within the warm and humid airmass spanning from the central U.S. to
the Southeast and Mid-Atlantic. Showers and thunderstorms are
expected both along and well- ahead of a cold front sinking
southeastward across the central Plains and Midwest, as well as
associated with diurnal monsoon activity across the southern
Rockies and adjacent High Plains. At the start of day 2, there's
the potential for ongoing late-night convection across south-
central MO as a remnant MCV and overnight low-level jet foster
slow-moving thunderstorms. There remains rather high uncertainty
regarding the maintenance of thunderstorm activity in this region
past the 12z Sun start time of Day 2, but should greater certainty
arise a Slight Risk may be needed for south-central MO and nearby
regions.

Meanwhile, organized convection firing along the advancing cold
front across the central Plains and Midwest should provide another
focus for potential slow-moving convection in the evening before
activity should become more progressive under the influence of a
strengthening cold pool and progressive cold front. PWs approaching
2" and near the 90th climatological percentile will provide the
opportunity for intense rainfall rates scattered 2-4" rainfall
totals between parts of KS, MO, and southern IA.

Elsewhere within the warm sector across the Mid-South, Mid-
Atlantic, Southeast, and Southern Rockies/High Plains, typical
summer thunderstorms exhibiting scattered and a pulse mode are
likely. These storms may contain briefly very intense rainfall
rates, but see updrafts collapse quickly and become outflow
dependent. Where convective clusters merge or linger near a
stationary front draped across the Mid-Atlantic and central
Appalachians, isolated flash flooding is possible.

Snell/Bann

Day 3
Valid 12Z Tue Jul 01 2025 - 12Z Wed Jul 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN ROCKIES EASTWARD INTO THE MID ATLANTIC...

Similar to Sunday...convection is expected to develop within a region
of decent CAPE and precipitable water values in excess of 2
standard deviations above climatology. Except for some mid-level
westerly flow around the Great Lakes to provide some shear
there...the flow farther south should be fairly meager (but offset
by steeper low-level lapse rates). This sets up the potential for
some local rainfall rates in excess of 1 inch per hour that results
in excessive rainfall from the Southern Rockies/Western High
Plains east/northeastward into the Ohio Valley and parts of the
Mid- Atlantic region on Monday and Monday night. A weakening
surface boundary will help focus some of the threat for heavier
rainfall but its placement is quite uncertain. One area at the
moment that is being monitored for a potential upgrade to a Slight
Risk are parts of the Upper Ohio Valley and central Appalachians
(centered over western PA). The synoptic setup with a
stationary/warm front stretching across southern PA and an
approaching cold front from the west should help foster greater
coverage in showers/storms within a moist environment, but storm
motions within a mean column wind of 30kts could limit the
flooding threat even though this area remains sensitive to intense
rainfall. Therefor, a Marginal Risk was maintained to highlight the
threat for isolated flash flooding.

Snell/Bann


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4wrkJyYorcv7iR4Exc0_VZTaNhf3I3dIhtfmJR1b137n= BrDXEyX_Drbzg2rsVDWU8Zh8y0yz2tcNZ5dIfCpPD8aC4uw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4wrkJyYorcv7iR4Exc0_VZTaNhf3I3dIhtfmJR1b137n= BrDXEyX_Drbzg2rsVDWU8Zh8y0yz2tcNZ5dIfCpPUoMPba0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4wrkJyYorcv7iR4Exc0_VZTaNhf3I3dIhtfmJR1b137n= BrDXEyX_Drbzg2rsVDWU8Zh8y0yz2tcNZ5dIfCpPFz1lC2g$=20

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FOUS30 KWBC 122000 AAA
QPFERD

Excessive Rainfall Discussion...UPDATED
NWS Weather Prediction Center College Park MD
400 PM EDT Sat Jul 12 2025

Day 1
Valid 16Z Sat Jul 12 2025 - 12Z Sun Jul 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE
SOUTHERN PLAINS AND FOR PORTIONS OF NEW MEXICO...

...New Mexico and the Southern Plains...

A digging shortwave trough slowly moving across the Texas and
Oklahoma Panhandles and into Oklahoma tonight will act as a focus
for thunderstorms, as ample Gulf moisture streaming north across
the Southern Plains provides plentiful support for thunderstorms.
CAMs suggest there will be two separate areas of thunderstorms
today through tonight: One along the TX/OK border and a second one
near or over the Concho Valley, with perhaps a relative minimum of
activity in between. While this is the broader consensus (and not
wholesale), there is little agreement on how those storms will
evolve, including which areas will be hardest hit with the heaviest
rain. Given the sensitivity for heavy rain in the Concho Valley
especially, these prevalent uncertainties support keeping the
region in a very high end Slight Risk this morning. Morning
activity over West Texas is waning, but cloud cover is prevalent to
its east as of 16Z. Over northeast TX (~Metroplex) into OK,
sunshine is more abundant and there is a bit more support for
heavier rainfall later today per the 12Z CAMs.

Neighborhood probabilities (40km radius) in the 12Z HREF guidance
peak above 80% for 3 inches or more through much of the Slight Risk
area in Texas and Oklahoma. However, the EAS probs are much lower
which indicate little agreement on the smaller scale. This lends
credence to the high likelihood that there will be flash flooding,
but its magnitude and coverage remains very low confidence.

Further west into New Mexico, the Slight Risk remained to account
for the sensitivities of communities in the Sacramento Mountains
north to the Sangre de Cristos. The cold front over the TX
Panhandle will bring in some more stable air on the east side of
the state but this may help to focus activity to the west of the
front later today.

...Northeast and Mid-Atlantic...

Cold front over the Midwest will continue eastward today, with
nearly all areas eastward in the warm sector (warm front lifting
through northern NY this morning). Convection should fire this
afternoon along/ahead of the cold front, focused from Michigan
southward and southwestward which could support a localized flash
flooding threat. Rainfall rates of 1-2"/hr are possible with some
totals of 3-4" per some CAM guidance. It has been drier than normal
over the past 1-2 weeks, and the Marginal risk is sufficient.

Farther east, plentiful moisture and light flow in the lower half
of the column favors some afternoon convection that could yield
1-2.5"/hr rates. FFG values are lower in the Southern Tier or NY
into the Mid- Atlantic due to recent rainfall, and a Marginal risk
area covers this region from the I-81 to I-95 corridor (western New
England southward to the Carolinas).


Fracasso/Wegman

Day 2
Valid 12Z Sun Jul 13 2025 - 12Z Mon Jul 14 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF NEW
MEXICO, THE SOUTHERN PLAINS, AND THE MID- ATLANTIC...

...Southern Plains...

The upper level shortwave responsible for forcing the thunderstorms
from Saturday night will cut off from the primary flow with the jet
on Sunday. This upper level shortwave will coincide with a
stationary front over Northwest Texas and Oklahoma. There will be a
continuous southerly flow of plentiful Gulf moisture across Texas
and Oklahoma on Sunday, but with limited forcing, the overall
coverage of showers and thunderstorms will be lesser on Sunday as
compared with today (Sat). The tradeoff in some areas with this
setup is because both the stationary front and upper level cutoff
disturbance will be very slow-moving, if moving at all, some of the
same areas that will likely see heavy rain from thunderstorms for
the second consecutive day. This is most likely in north-central
Texas and southeastern Oklahoma. For this reason, a higher end
Slight was maintained for this area on our internal progs. While
storm coverage will be lesser, due to the abundant moisture
available for any storms, the stronger storms will be capable of 2+
inch/hour rainfall rates, which will be heavy enough to cause
localized flash flooding over sensitive areas. Depending on the
rainfall pattern/amounts in this area today and the next cycle of
CAM guidance, a focused Moderate Risk area could be needed.=20
Farther west, combination of the frontal boundary and a slight=20
surge in moisture should combine for another round of scattered=20
storms which could lead to additional flash flooding across=20
sensitive areas. In coordination with WFO ABQ, added a Slight Risk=20
over central NM given the uptick in QPF compared to today (Sun).

...Mid-Atlantic...

Very few changes were needed to the Slight Risk that covers much of
the central Appalachians from Virginia north through upstate New
York. Abundant Gulf and Atlantic moisture will stream northward up
the East Coast through the period, increasing PWATs locally to
over 2 inches. A potent cold front will cross out of the Midwest
and into Pennsylvania and New York Sunday night. This forcing will
result in numerous showers and thunderstorms capable of very heavy
rainfall in the Slight Risk area. The greatest rainfall totals are
likely from northern Pennsylvania through central New York. Further
south towards and west of the DMV, while forcing will be lesser,
any storms that form will be capable of heavy rainfall with
abundant moisture available.

...Eastern Florida...

A mid-level feature (NHC is monitoring for potential tropical
development) off the Southeast Coast will drift southwestward then
westward toward the southern half of Florida tomorrow/tomorrow
night. With it, PW values will rise to over 2 inches (>90th
percentile) and some heavy rainfall is possible which could lead
to some flash flooding, especially over the urban areas.

Fracasso/Wegman

Day 3
Valid 12Z Mon Jul 14 2025 - 12Z Tue Jul 15 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE
CENTRAL AND SOUTHERN FLORIDA PENINSULA...

...Florida...

The westward-moving mid-level wave will traverse the Florida
Peninsula on Monday, with an increase in PW values to over 2.25
inches (>95th percentile). The greatest rainfall and threat for
storms is expected during peak heating Monday afternoon coincident
with light winds in the lower half of the column. While there
remains considerable uncertainty as to convective evolution and
placement, the sheer volume of moisture available for any storms to
draw upon in the formation of heavy rain will be more than capable
of supporting heavy rain and resultant flash flooding. Much of
Florida has been dry for soil moisture and recent lack of rainfall,
so the drier than normal conditions will likely mitigate any
potential flash flooding. Urban areas such as the Miami-Ft
Lauderdale metro as well as Tampa and Orlando will be at a higher
risk for flash flooding due to the slow-moving storms, which will
likely interact via cold pools through the afternoon. Nudged the
Slight Risk southward to encapsulate the southern portion of the
Peninsula per coordination with WFO MFL.

...Southern New Mexico/Southeastern Arizona/Texas/Ozarks...

Weakening/dissipating front over northern Texas will become less of
a focus for rainfall, but there will still be lingering moisture
across the region. Maintained a broad Marginal Risk area over this
region as any additional rainfall over areas that may see several
inches of the next two days may cause a localized flash flooding
concern. Expanded the area westward into southeastern Arizona given
the expected surge in moisture from Mexico.

...East Coast...
Cold front will cross the Appalachians on Monday with another day
of scattered showers/storms ahead of the front. With PW values
remaining remaining above 1.75 inches (>90-95th percentile) and
rain from the previous two days, will continue a Marginal Risk
outline for this region.

...Northern Plains...
Frontal boundary across ND into MN will act as a focus for
scattered afternoon storms amid a increasing PW values to around
1.5 inches (~90th percentile). This could yield some 1"/hr rainfall
rates which may exceed local FFG values.

...Northwestern Montana...
Guidance indicates some modest rainfall moving into northwestern
Montana Monday afternoon/evening, which could capitalize on modest
instability present. Rainfall rates may not be too heavy but will
maintain the Marginal Risk in this region.


Fracasso/Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-rlvw2UOwWQNeEGJQ3AuJWD6MUaPi3dgZIBRI58Bxpfp= JG2-nnoAxLW_3OkbyBYIvmtx2kqKDWWJtA1vbt723D-iIro$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-rlvw2UOwWQNeEGJQ3AuJWD6MUaPi3dgZIBRI58Bxpfp= JG2-nnoAxLW_3OkbyBYIvmtx2kqKDWWJtA1vbt72aiMaSwA$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-rlvw2UOwWQNeEGJQ3AuJWD6MUaPi3dgZIBRI58Bxpfp= JG2-nnoAxLW_3OkbyBYIvmtx2kqKDWWJtA1vbt721fk6DNw$=20

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