725
ACUS11 KWNS 212000
SWOMCD
SPC MCD 211959
SDZ000-NDZ000-MTZ000-WYZ000-212200-
MESOSCALE DISCUSSION 1746
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT MON JUL 21 2025
AREAS AFFECTED...PORTIONS OF CENTRAL AND EASTERN MT INTO WESTERN
ND/SD AND NORTHEAST WY
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 211959Z - 212200Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...SEVERE THUNDERSTORM POTENTIAL WILL INCREASE OVER THE NEXT
1-3 HOURS. POTENTIAL FOR LARGE HAIL 2.5-3.0 INCHES IN DIAMETER,
DAMAGING GUSTS TO 80 MPH, AND POSSIBLY A TORNADO WILL BE POSSIBLE
INTO THE EVENING HOURS. A SEVERE THUNDERSTORM WATCH IS LIKELY FOR
PARTS OF THE DISCUSSION AREA BY 22Z.
DISCUSSION...ISOLATED THUNDERSTORMS AND INCREASING CUMULUS ARE NOTED
NEAR THE HIGHER TERRAIN OF NORTHERN WY/SOUTHERN MT. THIS ACTIVITY IS
DEVELOPING WITHIN DRIER AIR AND STRONG DIFFERENTIAL HEATING OVER
HIGHER TERRAIN AND AS INCREASING LARGE-SCALE ASCENT BEGINS TO
IMPINGE ON THE AREA FROM THE WEST. WITH TIME, ADDITIONAL CONVECTION
IS EXPECTED TO SPREAD NORTHEAST INTO AN AXIS OF GREAT BOUNDARY-LAYER
MOISTURE IN THE UPPER 50S TO LOW 60S F FROM CENTRAL MT INTO THE
WESTERN DAKOTAS.
FAVORABLE VERTICAL SHEAR AMID A ROUGHLY WEST TO EAST ORIENTED TONGUE
OF MODEST TO STRONG INSTABILITY WILL SUPPORT INITIAL CELLS CAPABLE
OF LARGE HAIL. STEEPENED LOW-LEVEL LAPSE RATES AND AT LEAST SOME
MODEST DRY AIR NOTED IN FORECAST SOUNDINGS CENTERED AROUND 700 MB
SUGGESTS STRONG WINDS ALSO WILL BE POSSIBLE. THIS MAY ESPECIALLY
OCCUR IF ANY CLUSTERS/BOWS DEVELOP AS A LOW-LEVEL JET INCREASES
DURING THE EVENING, AND WITH EASTWARD INTO THE WESTERN DAKOTAS. AS
STORMS INTERACT WITH THE MOIST AXIS ACROSS SOUTHEAST MT, SOME
POTENTIAL WILL EXIST FOR A TORNADO OR TWO IF CAPPING IS SUFFICIENTLY
ERODED AND WHERE BACKED LOW-LEVEL WINDS WILL RESULT IN LOCALLY
ENHANCED 0-1 KM SRH.
INITIAL SEVERE THUNDERSTORM WATCH ISSUANCE IS EXPECTED BY 22Z,
THOUGH EASTERN EXTENT OF WATCH ISSUANCE IS A BIT UNCERTAIN AND MAY
OR MAY NOT EXTEND INTO THE WESTERN DAKOTAS WITH THIS WATCH ISSUANCE.
..LEITMAN/SMITH.. 07/21/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...BIS...UNR...BYZ...GGW...TFX...
LAT...LON 44260422 44220359 44340317 44820295 45760286 46920302
47720348 48090542 47840790 47101010 46681056 46231074
45551031 45170739 44880570 44260422
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN
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