MESOSCALE DISCUSSION 0441
   NWS STORM PREDICTION CENTER NORMAN OK
   0655 AM CDT THU APR 11 2013
   
   AREAS AFFECTED...SOUTH CENTRAL AND SERN LA/SRN MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 111155Z - 111300Z
   
   PROBABILITY OF WATCH ISSUANCE...60 PERCENT
   
   SUMMARY...A TORNADO WATCH MAY BE NEEDED BY MID MORNING ACROSS SOUTH
   CENTRAL-SERN LA INTO SRN MS.  A LINE OF TSTMS DEVELOPING OVER SWRN
   LA IS EXPECTED TO EXPAND NNEWD AND SSWWD INTO A QUASI-LINER
   CONVECTIVE SYSTEM THIS MORNING AS IT ADVANCES EWD INTO THE MOIST AND
   DESTABILIZING WARM SECTOR OVER THE LOWER MS VALLEY.
   
   DISCUSSION...SURFACE OBSERVATIONS ACROSS THE DISCUSSION AREA SHOWED
   RICH MOISTURE ALREADY PRESENT /DEWPOINTS IN THE LOWER 70S ALONG THE
   SOUTH CENTRAL/SERN LA COAST TO MID-UPPER 60S IN SRN MS/. AT
   1130Z...REGIONAL RADAR IMAGERY SHOWED A BAND OF TSTMS INCREASING
   SOME IN INTENSITY AND COOLING CLOUD TOPS PER IR SATELLITE IMAGERY. 
   ALTHOUGH THIS ACTIVITY IS CURRENTLY POST-FRONTAL...00Z 4 KM WRF-NSSL
   AND NMM SUGGEST THESE STORMS WILL FURTHER GROW UPSCALE INTO A
   FORWARD PROPAGATING QLCS AS HEIGHT FALLS/DPVA WITH AN EJECTING
   SHORTWAVE TROUGH APPROACH THIS REGION. EFFECTIVE BULK SHEAR OF 40-50
   KT WITH VECTORS ORIENTED PARALLEL TO THE FRONT/INITIATING BOUNDARY
   FAVOR LINEAR ORGANIZATION. WHILE DAMAGING WINDS WILL BE A
   THREAT...THE HIGHER MOISTURE CONTENT AIR /SURFACE DEWPOINTS AROUND
   70 F/ AND ENHANCED LOW LEVEL SHEAR PER BACKED SELY SURFACE WINDS AND
   STRENGTHENING SLY LLJ WILL SUPPORT A TORNADO THREAT. VWP DATA AT
   SLIDELL LA WSR-88D INDICATED LOW LEVEL HODOGRAPH CURVATURE AND SFC-1
   KM SHEAR OF 30 KT AND 0-1 KM SRH OF 225 M2/S2 --- MORE THAN
   SUFFICIENT FOR A TORNADO THREAT.
   
   ..PETERS/MEAD.. 04/11/2013
   
   
   ATTN...WFO...MOB...JAN...LIX...LCH...
   
   LAT...LON   29259316 31319189 32319107 32599073 32478893 31798864
               30328856 29508873 28818922 28719001 28929124 29259316