MESO: Mesoscale Discussion 1290

ACUS11 KWNS 262007
SWOMCD
SPC MCD 262006
NDZ000-SDZ000-MTZ000-262100-

MESOSCALE DISCUSSION 1290
NWS STORM PREDICTION CENTER NORMAN OK
0306 PM CDT TUE JUN 26 2012

AREAS AFFECTED...PORTIONS OF NE AND ERN MT...WRN ND...NW SD

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 262006Z - 262100Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...SEVERE THREAT IS INCREASING THIS AFTERNOON AS SFC HEATING
CONTINUES TO ERODE STRONG CAP. SHOULD STORMS DEVELOPED...ISOLATED
CONVECTION WILL BE CAPABLE OF STRONG/DAMAGING WINDS AND LARGE HAIL.
A SVR WW MAY BE NEEDED BY 22Z.

DISCUSSION...LATEST VIS SATELLITE IMAGERY SHOWED CUMULUS DEVELOPING
ALONG/NEAR MOISTURE GRADIENT FROM THE BLACK HILLS NWWD TOWARD JORDAN
MT. AS TEMPERATURES HAVE WARMED INTO THE MID 90S TO NEAR 100 DEGREES
ACROSS MUCH OF THE MCD AREA...THE CAP HAS WEAKENED CONSIDERABLY AND
KUDX RADAR WAS SHOWING SOME WEAK ECHOES IN BUTTE COUNTY SD. IF
STORMS CAN BECOME ESTABLISHED...WHICH IS BECOMING INCREASINGLY
LIKELY WITH CONTINUED HEATING/DESTABILIZATION...STRONG/DAMAGING
WINDS AND LARGE HAIL ARE EXPECTED. STRONG DEEP LAYER SHEAR VEERING
SLIGHTLY WITH HEIGHT BASED ON VAD WIND PROFILES FROM GGW AND BIS
WILL FAVOR ROTATING SUPERCELL STRUCTURES. STEEP LAPSE RATES AND
DCAPE VALUES IN EXCESS OF 1500 J/KG WILL FAVOR DOWNBURST WINDS AND
WITH STORMS MOVING INTO AN EXTREME CAPE ENVIRONMENT...LARGE HAIL
WILL ALSO BE POSSIBLE. GIVEN STRONG UPPER RIDGE AND RATHER WEAK
UPPER FORCING FOR ASCENT...STORM COVERAGE MAY REMAIN RATHER
ISOLATED. TRENDS WILL CONTINUE TO BE MONITORED AND A WW MAY BE
NEEDED BY 22Z.

..LEITMAN/WEISS.. 06/26/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...ABR...BIS...UNR...BYZ...GGW...TFX...

LAT...LON 44710350 45590424 46950571 47400746 47790807 48380837
48990815 49000797 48960297 48250161 46060048 44850125
44100203 43830294 44710350

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