969
ACUS11 KWNS 271741
SWOMCD
SPC MCD 271740
MTZ000-WYZ000-272015-
MESOSCALE DISCUSSION 1348
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM CDT SAT JUN 27 2026
AREAS AFFECTED...EASTERN MONTANA AND NORTHEAST WYOMING
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 271740Z - 272015Z
PROBABILITY OF WATCH ISSUANCE...95 PERCENT
SUMMARY...SEVERE STORMS ARE EXPECTED TO DEVELOP BY 19-20Z WITH AN
ASSOCIATED RISK FOR WIND GUSTS OF 80+ MPH, LARGE TO VERY LARGE HAIL
OF 2+ INCHES, AND PERHAPS A TORNADO OR TWO. A WATCH IS LIKELY.
DISCUSSION...LATEST MESOANALYSIS PLACED A SURFACE LOW OVER FAR
SOUTHEAST MT OR NORTHEAST WY WITH AN ASSOCIATED STATIONARY FRONT OR
TROUGH STRETCHING FROM NORTHWEST ND TO THE VICINITY OF THE BIG HORN
MOUNTAINS IN NORTH-CENTRAL WY. A CORRIDOR OF HIGHER BOUNDARY-LAYER
MOISTURE CONTENT RESIDES ALONG AND TO THE NORTH OF THE FRONT, WHICH
COINCIDES WITH THE NORTHERN EDGE OF AN EML PLUME, SUPPORTING MLCAPE
OF 1000-1500 J/KG, PER LATEST OBJECTIVE ANALYSIS. DAYTIME HEATING
AND INCREASING HEIGHT FALLS/FORCING FOR ASCENT ARE EXPECTED TO
SUPPORT FURTHER AIR MASS DESTABILIZATION BY EARLY TO MID AFTERNOON,
WHILE A CAPPING INVERSION FOR SURFACE-BASED PARCELS BECOMES
PROGRESSIVELY WEAKER.
LATEST SHORT-TERM MODEL GUIDANCE INDICATES AN INCREASED LIKELIHOOD
OF SURFACE-BASED THUNDERSTORM DEVELOPMENT BY 19-20Z ALONG THE BIG
HORN MOUNTAINS. THAT NOTION IS CORROBORATED BY THE DEEPENING CUMULUS
FIELD ALONG THAT TERRAIN FEATURE, PER RECENT VISIBLE SATELLITE
TRENDS. RAP-BASED FORECAST SOUNDINGS IN THAT AREA INDICATE 40-50 KT
OF NORTH-NORTHEAST DEEP-LAYER SHEAR SUPPORTIVE OF SUPERCELLS AS THE
INITIAL STORM MODE WITH THE PRIMARY HAZARD BEING LARGE TO VERY LARGE
HAIL. WHILE LOW-LEVEL SHEAR ISN'T FORECAST TO BE PARTICULARLY
STRONG, THE PRESENCE OF THE FRONT MAY SERVE AS A LOCAL VORTICITY
SOURCE FOR SOME TORNADO THREAT. BY LATE AFTERNOON INTO EARLY
EVENING, THERE IS GOOD MODEL AGREEMENT IN STORMS COALESCING INTO A
BROADER-SCALE, BOWING STRUCTURE CAPABLE OF SWATHS OF DAMAGING WINDS,
INCLUDING GUSTS OF 80+ MPH.
..MEAD/GUYER.. 06/27/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...UNR...BYZ...GGW...RIW...
LAT...LON 44850544 44650596 44430686 44790821 45260856 46460754
47520711 47920690 48380577 48090460 47800451 46950419
46080435 45130465 44850544
MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page