MESOSCALE DISCUSSION 0837
   NWS STORM PREDICTION CENTER NORMAN OK
   0338 PM CDT SAT MAY 21 2011
   
   AREAS AFFECTED...NRN LA...FAR SRN AR
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 212038Z - 212215Z
   
   AN ISOLATED THREAT FOR MARGINALLY SEVERE HAIL/DAMAGING WIND MAY
   CONTINUE THROUGH EARLY EVENING. PROBABILITY OF A SEVERE TSTM WATCH
   ISSUANCE BY 22Z IS 20 PERCENT.
   
   TSTM CLUSTERS HAVE PERSISTED ACROSS NRN LA THROUGH MUCH OF THE DAY
   LIKELY AS A RESULT OF LOW-LEVEL WARM THETA-E ADVECTION ATOP AN
   OUTFLOW BOUNDARY IN THE WAKE OF AN EARLY MORNING MCS.
   OVERALL...CORES WITHIN THESE CLUSTERS HAVE SHOWN SOME
   INTENSIFICATION IN RADAR REFLEXIVITY DURING THE PAST HOUR. THIS
   ACTIVITY IS BEING FED BY A MODERATELY UNSTABLE ENVIRONMENT S OF THE
   OUTFLOW BOUNDARY CHARACTERIZED BY MLCAPE OF 1500 TO 2500 J/KG.
   ALTHOUGH EFFECTIVE SHEAR OF 25 TO 35 KT WOULD BE SUFFICIENT FOR
   ORGANIZED UPDRAFTS...VEER-BACK-VEER WIND PROFILES SHOULD CONTINUE TO
   FOSTER A MORE PULSE-LIKE NATURE TO UPDRAFTS. THIS SHOULD PRIMARILY
   YIELD ISOLATED MARGINALLY SEVERE HAIL AND WET MICROBURSTS.
   
   ..GRAMS.. 05/21/2011
   
   
   ATTN...WFO...JAN...LZK...SHV...
   
   LAT...LON   32999379 33419316 33399179 33079143 32579127 32079131
               31739146 31649174 31779236 32189327 32549373 32999379