MESOSCALE DISCUSSION 0979 NWS STORM PREDICTION CENTER NORMAN OK 1207 PM CDT WED MAY 30 2012 AREAS AFFECTED...SE AR...WRN MS...NE LA CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 301707Z - 301830Z PROBABILITY OF WATCH ISSUANCE...60 PERCENT SUMMARY...AN ISOLATED THREAT FOR HAIL AND WIND DAMAGE WILL LIKELY DEVELOP ACROSS THE LOWER TO MID MS VALLEY THIS AFTERNOON. AS THE STORMS INTENSIFY...WW ISSUANCE WILL BE POSSIBLE ACROSS THE REGION. DISCUSSION...A SHORT LINE SEGMENT IS CURRENTLY ONGOING JUST TO THE EAST OF LITTLE ROCK AR LOCATED ON THE LEADING EDGE OF STRONG LARGE-SCALE ASCENT ASSOCIATED WITH A PRONOUNCED SHORTWAVE TROUGH MOVING ACROSS THE MS RIVER IN FAR SRN IL. THE STORMS ARE ALSO LOCATED ON THE FAR NRN EDGE OF MODERATE INSTABILITY WITH MESOANALYSIS ESTIMATING MLCAPE IN THE 1000 TO 1500 J/KG RANGE ACROSS NE LA...SE AR AND WCNTRL MS. THE INSTABILITY ALONG WITH ABOUT 30 KT OF DEEP LAYER SHEAR EVIDENT ON REGIONAL WSR-88D VWPS SHOULD BE SUFFICIENT FOR SEVERE MULTICELL LINE SEGMENTS. AS DESTABILIZATION CONTINUES EARLY THIS AFTERNOON AND LOW-LEVEL LAPSE RATES STEEPEN...A WIND DAMAGE THREAT SHOULD DEVELOP. IN ADDITION...A POCKET OF STEEP MID-LEVEL LAPSE RATES IS ANALYZED OVER SE AR AND NW MS WITH 850 TO 500 MB LAPSE RATES OF 7.5 C/KM. THIS SHOULD RESULT IN AN ISOLATED LARGE HAIL THREAT ESPECIALLY AS INSTABILITY CONTINUES TO INCREASE OVER THE NEXT FEW HOURS. ..BROYLES/WEISS.. 05/30/2012 ATTN...WFO...MEG...JAN...LZK...SHV...
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