MESOSCALE DISCUSSION 1483, AREAS AFFECTED...SERN MT...WRN ND/SD

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MESOSCALE DISCUSSION 1483 NWS STORM PREDICTION CENTER NORMAN OK 0144 PM CDT TUE JUL 17 2012 AREAS AFFECTED...SERN MT...WRN ND/SD CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 171844Z - 171945Z PROBABILITY OF WATCH ISSUANCE...40 PERCENT SUMMARY...ALTHOUGH A FEW ELEVATED THUNDERSTORMS ARE OCCURRING OVER THE BLACK HILLS...THE AREA IS BEING MONITORED FOR ADDITIONAL...MORE ORGANIZED DEVELOPMENT. DISCUSSION...AN ERN GREAT BASIN VORTICITY MAX HAS REACHED N CNTRL WY /PER 1830Z WV IMAGERY/. THE IMPLIED FORCING FOR ASCENT IN COMBINATION WITH A WEAK LEE SURFACE TROUGH EXTENDING FROM SERN MT INTO NERN WY AND THE HIGHER TERRAIN OF THE BLACK HILLS MAY PROVIDE SEVERAL MUDDLED AREAS OF INCREASED VERTICAL DEVELOPMENT. HI-RES CONSENSUS GENERALLY SUPPORTS CONVECTIVE DEVELOPMENT ACROSS THESE AREAS WITHIN THE NEXT FEW HOURS...POSSIBLY EVOLVING INTO A LOOSELY ORGANIZED CLUSTER ACROSS THE DAKOTAS GIVEN SUFFICIENT LOW-LEVEL MOISTURE /SURFACE DEW POINTS IN THE LOWER 60S F/ AND 8 C/KM MID-LEVEL LAPSE RATES PER 12Z RAP SOUNDING. HOWEVER...WEAK AND DISORGANIZED SHEAR PROFILES MAY LIMIT OVERALL ORGANIZATION...WITH COVERAGE OF EXPECTED SEVERE STORMS UNCERTAIN AT THIS TIME. ..HURLBUT/MEAD.. 07/17/2012 ATTN...WFO...BIS...UNR...BYZ... LAT...LON 43860478 44310541 45500535 46410510 46280394 45940350 44800316 44010338 43660431 43860478