ACUS11 KWNS 131944
SWOMCD
SPC MCD 131944=20
MTZ000-132115-

Mesoscale Discussion 1594
NWS Storm Prediction Center Norman OK
0244 PM CDT Sat Jul 13 2024

Areas affected...northern into eastern Montana

Concerning...Severe potential...Watch likely=20

Valid 131944Z - 132115Z

Probability of Watch Issuance...80 percent

SUMMARY...The severe threat is increasing across portions of
northern into eastern Montana this afternoon. Severe wind and hail
are the main threats. A WW issuance is likely within the next hour
or so to address the impending severe threat.

DISCUSSION...Remnant convection across southwestern MB (Canada) has
produced an outflow boundary that is currently situated from roughly
the SK/MB/MT border to Richland County, MT. The boundary layer
continues to destabilize along this outflow boundary, where visible
satellite shows rapidly deepening CU, and MRMS mosaic radar imagery
showing the first signs of convective initiation. 19Z mesoanalysis
shows a 500 mb speed max with small embedded vort maxima pivoting
around the northern periphery of an anticyclone centered over the
central Rockies, which will also provide enough lift for
thunderstorm development. Along the outflow boundary, upslope flow
is contributing to low-level southeasterly winds beneath stronger
westerly mid-level flow (driven by the approaching 500 mb speed
max), resulting in 50+ kts of effective bulk shear in the form of
elongated, straight hodographs. With upper 50s/low 60s F surface
dewpoints beneath 7-8 C/km mid-level lapse rates also supporting
2000 J/kg MLCAPE, supercell storm modes are favored early on. Severe
wind and hail will be possible (and an instance of 2+ inch diameter
hail cannot be ruled out).

Some high-resolution convection-allowing guidance shows
thunderstorms growing upscale into a bow echo MCS, and this scenario
is plausible given the potential for adequate evaporative cooling
within a well-mixed boundary layer. Should this occur, a focused
corridor of severe winds could develop later this afternoon. A
Severe Thunderstorm Watch will be needed within the next hour or so.

..Squitieri/Hart.. 07/13/2024

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7KLKPw8r4GqAYOvriTuElck9aUvu3dlNA21d7VIxVA-pXQCkdi0lcxmmGHAvfoMNxpKvXAoRS= n86V8JHWRcWepnTLpM$ for graphic product...

ATTN...WFO...BYZ...GGW...TFX...

LAT...LON 48981067 48930793 48560523 47850404 47180406 46660458
46840610 47130794 47470902 47891006 48981067=20


=3D =3D =3D
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