MESOSCALE DISCUSSION 0523
   NWS STORM PREDICTION CENTER NORMAN OK
   0918 PM CDT SAT APR 18 2009
   
   AREAS AFFECTED...PARTS OF S-CNTRL LA AND EXTREME SWRN MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 190218Z - 190315Z
   
   A NON-ZERO TORNADO THREAT APPEARS TO BE PERSISTING WITH DISCRETE
   ELEMENTS EXHIBITING SUPERCELL STRUCTURE EMBEDDED WITHIN LARGE RAIN
   SHIELD OVER SRN LA.  CONVECTIVE TRENDS WILL BE MONITORED AS MCS
   SLOWLY PUSHES EWD OVER LA AND ADJACENT COASTAL WATERS.
   
   RADAR MOSAIC SHOWS COMPLEX CONVECTIVE EVOLUTION IS UNDERWAY AS BOW
   ECHO HAS BECOME MORE DIFFUSE WITH A TREND FROM QUASI-LINEAR TO
   QUASI-DISCRETE STRUCTURES OCCURRING IN THE PAST 90 MINUTES.  LATEST
   SURFACE ANALYSIS SHOWS A PRESSURE TROUGH EXTENDING FROM SW TO NE
   FROM 30 MI SE LCH TO 25 N BTR.  AS STORMS DEVELOP JUST INLAND AND
   MOVE NNE...IT APPEARS THE BEST LOW LEVEL ROTATION IS ACQUIRED WITHIN
   THE AFOREMENTIONED AXIS...WHERE LOW LEVEL WINDS ARE BACKED TO ELY. 
   WITH ONLY MODEST AVAILABLE CONVECTIVE INSTABILITY...DEEP MOIST AND
   STRONGLY SHEARED ENVIRONMENT MAY CONTINUE TO BE SUPPORTIVE OF
   TRANSIENT STORM SCALE ROTATION AT TIMES.  WITH THAT SAID...A
   SOMEWHAT LIMITED BUT NON-ZERO TORNADO THREAT MAY CONTINUE TO EXIST
   FOR THE NEXT HOUR OR TWO.
   
   ..SMITH.. 04/19/2009
   
   
   ATTN...WFO...LIX...LCH...
   
   LAT...LON   29809322 30619219 31019145 30889084 30589078 30329114
               29799209 29649252 29519301 29809322