MESOSCALE DISCUSSION 0833
   NWS STORM PREDICTION CENTER NORMAN OK
   0127 AM CDT SAT MAY 21 2011
   
   AREAS AFFECTED...UPPER COASTAL PLAIN/SOUTHEAST TX AND
   WESTERN/NORTHERN LA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 210627Z - 210800Z
   
   IN ADDITION TO LOCALLY HEAVY RAINFALL...ISOLATED DAMAGING WINDS
   AND/OR A BRIEF TORNADO WILL BE POSSIBLE OVERNIGHT ACROSS THE UPPER
   TX COASTAL PLAIN/SOUTHEAST TX AND WESTERN/NORTHERN LA.
   
   A COMPOSITE SQUALL LINE/QLCS CONTINUES TO PROGRESS GENERALLY
   EASTWARD ACROSS SOUTHERN AR/INTO NORTHWEST LA AND ACROSS EAST TX AS
   OF 0615Z...WITH SEVERAL EMBEDDED/FASTER FORWARD PROPAGATING ELEMENTS
   /40+ KT MOVEMENT IN SOME CASES/ NOTED WITHIN THE BROADER CONVECTIVE
   LINE. WHILE CINH HAS NOCTURNALLY INCREASED...A RELATIVELY
   MOIST/UNSTABLE AIRMASS EXISTS ACROSS THE TX COASTAL PLAIN INTO
   WESTERN LA WHERE SURFACE DEWPOINTS ARE IN THE LOWER 70S F. WHILE A
   WIDESPREAD SEVERE RISK IS NOT ANTICIPATED LARGELY OWING TO
   AFOREMENTIONED CINH/WEAK LOW LEVEL LAPSE RATES...ISOLATED DAMAGING
   WIND GUSTS AND/OR A TORNADO CANNOT BE RULED OUT OVERNIGHT GIVEN
   RESIDUAL HIGH MOISTURE CONTENT/STEEP LAPSE RATES ALOFT AS PER 00Z
   LAKE CHARLES OBSERVED RAOB...WITH EFFECTIVE SRH ESTIMATED TO BE ON
   THE ORDER OF 150-200 M2/S2. LOCALLY HEAVY RAINFALL WILL BE A CONCERN
   AS WELL.
   
   ..GUYER.. 05/21/2011
   
   
   ATTN...WFO...JAN...LCH...SHV...HGX...
   
   LAT...LON   30199613 30379557 30969437 31829383 32609349 32679220
               31669196 30429246 29859370 29489534 29899628 30199613