MESOSCALE DISCUSSION 1019 NWS STORM PREDICTION CENTER NORMAN OK 0105 PM CDT SAT JUN 02 2012 AREAS AFFECTED...PORTIONS OF ERN IA...FAR ERN MO...MUCH OF IL...CNTRL/WRN IND CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 021805Z - 022000Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...A FEW STORMS MAY CONTAIN MARGINALLY SVR HAIL/WIND THIS AFTERNOON. THE LIMITED POTENTIAL OF SVR STORMS WILL LIKELY PRECLUDE THE ISSUANCE OF A WW. DISCUSSION...RECENT WATER VAPOR IMAGERY INDICATES A RIBBON OF MID/UPPER ASCENT IN ASSOCIATION WITH DCVA ATTENDANT TO AN UPPER JET OVER THE SWRN FLANK OF THE BROAD CYCLONIC CIRCULATION ENVELOPING THE NERN QUARTER OF THE CONUS. BENEATH THIS ASCENT...TOWERING CUMULUS CONTINUES TO DEVELOP INVOF /1/ A SFC TROUGH AXIS THAT IS SHIFTING SEWD ACROSS CNTRL/ERN IA...AND /2/ A SFC DEWPOINT GRADIENT EXTENDING FROM FAR NERN IA ACROSS FAR SWRN WI AND INTO NRN IL AND NRN IND. THESE FEATURES WILL SERVE AS THE FOCI FOR CONVECTIVE DEVELOPMENT INTO THE AFTERNOON. DESTABILIZATION OWING TO AREAS OF INSOLATION/DIABATIC HEATING AND THE AFOREMENTIONED MID/UPPER ASCENT WILL LIKELY ALLOW CONVECTION TO DEEPEN WHILE TRACKING SEWD/ESEWD. WHILE LOW-LEVEL MOISTURE IS RATHER MEAGER -- I.E. SFC DEWPOINTS IN THE UPPER 40S AND THE LOWER 50S -- STEEP LAPSE RATES ASSOCIATED WITH COLD MID-LEVEL TEMPERATURES /-20C TO -18C AT 500 MB PER 12Z RAOBS/ WILL SUPPORT MARGINAL DESTABILIZATION WITH MLCAPE VALUES OF 300-800 J/KG /HIGHEST OUTSIDE OF CONVECTIVE DEBRIS CLOUDS OVER CNTRL IL/. AND...WITH MODERATE/STRONG WNWLY/NWLY FLOW OVER THE AREA...20-30 KT OF EFFECTIVE BULK SHEAR WILL SUPPORT OCCASIONALLY ORGANIZED CONVECTIVE STRUCTURES INCLUDING MULTICELL STORMS WITH A THREAT FOR SVR WIND/HAIL. HOWEVER...THE LACK OF RICHER LOW-LEVEL MOISTURE AND LACK OF GREATER INSTABILITY SHOULD LIMIT THE POTENTIAL OF SVR STORMS. STORMS WILL DECREASE IN NUMBER/INTENSITY AS NOCTURNAL STABILIZATION COMMENCES EARLY THIS EVENING. ..COHEN/CARBIN.. 06/02/2012 ATTN...WFO...IWX...IND...PAH...LOT...ILX...LSX...DVN...
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