MESOSCALE DISCUSSION 0943

        MESOSCALE DISCUSSION 0943     NWS STORM PREDICTION CENTER NORMAN OK     0459 PM CDT MON MAY 28 2012          AREAS AFFECTED...EXTREME ERN IA THROUGH NRN IL          CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE           VALID 282159Z - 282330Z          PROBABILITY OF WATCH ISSUANCE...40 PERCENT          SUMMARY...STORMS DEVELOPING FROM ERN IA INTO NRN IL WILL POSE A     THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL THIS EVENING. WW     ISSUANCE WILL ULTIMATELY DEPEND ON CONVECTIVE TRENDS...AND IF STORMS     CONTINUE TO INCREASE IN COVERAGE AND INTENSITY...A SEVERE TSTM WATCH     MAY BE NEEDED.          DISCUSSION...RECENT TRENDS HAVE BEEN FOR STORMS TO INCREASE IN     COVERAGE WITHIN ZONE OF FRONTAL CONVERGENCE FROM ERN IA...EXTREME     NWRN IL AND CNTRL WI. DOWNSTREAM THE WARM SECTOR IS MODERATELY     UNSTABLE OVER NRN IL WITH 2000-2500 J/KG MLCAPE AND 7.5 C/KM 700-500     MB LAPSE RATES. LOW LEVEL WINDS HAVE VEERED AHEAD OF THE FRONT WHICH     IS SERVING TO LIMIT CONVERGENCE TO SOME DEGREE. ALOFT A WEAK IMPULSE     WAS INDICATED ON THE RAPID REFRESH ANALYSIS LIFTING NEWD THROUGH IA.     NEVERTHELESS...BOUNDARY LAYER TEMPERATURES HAVE CLIMBED TO AROUND 90     CONTRIBUTING TO A RELATIVELY WEAK CAP...AND STORMS MAY CONTINUE     DEVELOPING AS THE FRONT ADVANCES INTO NRN IL. WHILE SHEAR IN THE     WARM SECTOR IS WEAK...STRONGER FLOW ALOFT HAS OVERTAKEN THE FRONTAL     ZONE RESULTING IN 35-40 KT UNIDIRECTIONAL EFFECTIVE DEEP LAYER     SHEAR. BOTH MULTICELL LINE SEGMENTS AND POSSIBLY SOME SUPERCELL     MODES MAY OCCUR.          ..DIAL/HART.. 05/28/2012               ATTN...WFO...LOT...ILX...DVN...          LAT...LON   41509100 42408990 42278799 40858926 40519187 41509100