049
ACUS11 KWNS 121933
SWOMCD
SPC MCD 121932
SDZ000-MTZ000-WYZ000-122200-
MESOSCALE DISCUSSION 2067
NWS STORM PREDICTION CENTER NORMAN OK
0232 PM CDT FRI SEP 12 2025
AREAS AFFECTED...CENTRAL MONTANA INTO NORTHEASTERN WYOMING AND FAR
WESTERN SOUTH DAKOTA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 121932Z - 122200Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...THUNDERSTORM DEVELOPMENT IS EXPECTED TO CONTINUE ACROSS
THE HIGH TERRAIN AND ADJACENT AREAS IN CENTRAL MONTANA, NORTHEASTERN
WYOMING, AND FAR WESTERN SOUTH DAKOTA. AN ISOLATED WIND AND HAIL
RISK WILL BE POSSIBLE BEFORE MORE WIDESPREAD SEVERE STORMS DEVELOP
THIS EVENING.
DISCUSSION...A COUPLE OF AREAS OF THUNDERSTORM DEVELOPMENT ARE NOTED
NEAR THE BIG HORNS IN WYOMING, CENTRAL MONTANA MOUNTAINS, AND NEAR
THE BLACK HILLS IN SOUTH DAKOTA. THE MORE PROMINENT UPPER-LEVEL
FORCING FOR ASCENT REMAINS ACROSS PORTIONS OF AZ/CO, WHICH WILL
LIKELY KEEP THE RISK SOMEWHAT INITIALLY ISOLATED AND TIED TO THE
TERRAIN. GIVEN THE WEAKENING MLCIN AND HEATING/DESTABILIZATION AMID
DEEP LAYER SHEAR AROUND 30-40 KTS, THESE THUNDERSTORMS WILL BE
CAPABLE OF A FEW INSTANCES OF STRONG TO SEVERE WIND AND MARGINALLY
SEVERE HAIL.
AS THE UPPER-LEVEL WAVE APPROACHES THIS EVENING, FURTHER COOLING
ALOFT AND FORCING FOR ASCENT SHOULD PROMOTE MORE BROADER SCALE AIR
MASS DESTABILIZATION, INCREASING SHEAR, AND INCREASE IN THUNDERSTORM
ACTIVITY MOVING OFF THE TERRAIN POSING AN INCREASED RISK FOR LARGE
HAIL AND DAMAGING WIND.
..THORNTON/GUYER.. 09/12/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...UNR...CYS...BYZ...GGW...RIW...TFX...
LAT...LON 46121051 47181056 48970846 48870574 43810321 43050395
43180562 46121051
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN
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