ACUS11 KWNS 201833
SWOMCD
SPC MCD 201832=20
MTZ000-IDZ000-202130-

Mesoscale Discussion 1381
NWS Storm Prediction Center Norman OK
0132 PM CDT Fri Jun 20 2025

Areas affected...parts of southwest into west-central Montana

Concerning...Severe potential...Watch unlikely=20

Valid 201832Z - 202130Z

Probability of Watch Issuance...20 percent

SUMMARY...Scattered storms will form over much of southwest Montana
and into Idaho, and spread northeastward toward central Montana.
Scattered strong to severe gusts along with marginal hail may occur.

DISCUSSION...Visible satellite imagery shows strong heating over
much of the region ahead of the upper trough/midlevel temperature
gradient. The exception is north of the stationary front near GTF
where thick low-level clouds exist with cool north winds. Convection
is already increasing over the higher terrain from central ID into
southwest MT, and more substantial storms are likely to develop by
about 20-21Z.=20

GPS PWAT sensors currently indicate around 0.80-0.95 inches, which
is sufficient to support robust convection given steepening lapse
rates. Deep-layer shear around 50 kt may support cells producing
isolated hail near severe thresholds. While temperatures are cooler
downstream, some of that air should mix out given persistent
boundary layer mixing/heating upstream. Moderate winds aloft and
steepening boundary layer lapse rates may support
northeastward-moving bowing structures capable of producing damaging
gusts toward central MT.

..Jewell/Hart.. 06/20/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-FhHPtsWHz76bw9rAz40WxVJphE4RJ6NtpxDCVGPNlyV8KMarERFomMjQULCAnJuKpWPS6V0D= lbs2GSn6D7eUQf8OWA$ for graphic product...

ATTN...WFO...BYZ...TFX...MSO...

LAT...LON 46531391 47091288 47351210 47631068 47521003 46871004
46001085 45551131 45391155 44861253 44641358 44961425
45231454 45771465 46041451 46531391=20

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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