MESOSCALE DISCUSSION 0521
   NWS STORM PREDICTION CENTER NORMAN OK
   0724 PM CDT SAT APR 18 2009
   
   AREAS AFFECTED...SRN LA
   
   CONCERNING...TORNADO WATCH 166...
   
   VALID 190024Z - 190100Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 166 CONTINUES.
   
   TORNADO WATCH WILL BE ALLOWED TO EXPIRE AT 01Z.  
   
   EXPANSIVE MCS OVER THE NWRN GULF OF MEXICO AND SWRN LA WILL LIKELY
   CONTINUE EWD OVER S-CNTRL AND SERN LA IN CONJUNCTION WITH MESO-LOW
   /INVOF CAMERON PARISH AT 0020Z/ DURING THE EVENING HOURS.  LAST HOUR
   TRENDS IN RADAR MOSAIC SHOW A WEAKENING TREND WITH CONVECTION ALONG
   THE LA COAST /CAMERON PARISH/ BUT BRIEF/WEAK CYCLONIC CIRCULATIONS
   HAVE BEEN OBSERVED IN SWRN LA.  AS SUCH...TORNADO POTENTIAL...ALBEIT
   LIMITED...REMAINS IN THE NEAR TERM ACROSS PARTS OF SWRN LA.
   
   00Z SURFACE ANALYSIS DEPICTS LOWER QUALITY MOISTURE OVER SERN LA
   WITH DEWPOINTS ONLY IN THE MIDDLE 60S F COMPARED TO OBSERVATIONS
   EARLY TODAY OVER SWRN LA WITH DEWPOINTS IN THE UPPER 60S.  WITH ONLY
   MODEST MID-LEVEL LAPSE RATES AROUND 7 C/KM IN THE H7-H5 LAYER PER
   00Z LIX RAOB AND SURFACE TEMPS EXPECTED TO REMAIN IN THE LOWER
   70S...WILL MOST LIKELY LEAD TO A GENERAL WANING IN THE OVERALL
   SEVERE THREAT AS MCS PUSHES E INTO MORE MARGINAL THERMODYNAMIC
   ENVIRONMENT.  AS A RESULT...A WW IS NOT EXPECTED DOWNSTREAM OF WW
   166 OVER SERN LA.
   
   ..SMITH.. 04/19/2009
   
   
   ATTN...WFO...JAN...LIX...LCH...
   
   LAT...LON   29189216 29359379 29739391 30109376 30449311 30949246
               31039161 30989078 30409030 29859035 29279059 29119131
               29189216