MESOSCALE DISCUSSION 0581
   NWS STORM PREDICTION CENTER NORMAN OK
   0937 PM CDT MON APR 25 2011
   
   AREAS AFFECTED...N-CENTRAL THROUGH E TX...WRN LA.
   
   CONCERNING...TORNADO WATCH 204...205...
   
   VALID 260237Z - 260400Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 204...205...CONTINUES.
   
   CLUSTER OF STG-SVR TSTMS...WITH EMBEDDED SUPERCELLS BEARING
   TORNADO/HAIL/WIND DAMAGE RISK...CONTINUES TO MOVE ESEWD ACROSS
   E-CENTRAL TX TOWARD LFK AREA.  ACTIVITY WILL BE IN SOME COUNTIES OF
   WW 204 AFTER SCHEDULED 03Z EXPIRATION...AND STILL MAY BE UNDERWAY
   NEAR 04Z EXPIRATION OF WW 205.  THEREFORE EITHER WW MAY BE EXTENDED
   IN TIME FOR AREAS STILL TO BE AFFECTED BY THIS ACTIVITY. 
   CONVECTIVE/INSTABILITY TRENDS WILL BE MONITORED FOR POSSIBILITY OF
   ADDITIONAL WW OVER SE TX AND ADJACENT PORTIONS LA.
   
   ENVIRONMENTAL MLCINH IS INCREASING WITHIN 50-75 NM AHEAD OF THESE
   TSTMS...BASED ON MODIFIED LCH/SHV RAOBS AND RUC SOUNDINGS. 
   HOWEVER...UPDRAFT ENHANCEMENTS DUE TO INTERNAL DYNAMICS OF THESE
   TSTMS MAY OVERCOME SUBCLOUD STABILIZATION...AND FORCE LIFTED PARCELS
   TO REMAIN ROOTED NEAR SFC.  IF THIS KEEPS OCCURRING UNTIL ACTIVITY
   REACHES CONSIDERABLY MORE MOIST AIR MASS OVER PORTIONS SE TX AND
   SWRN/W-CENTRAL LA...COMPLEX MAY PERSIST FOR SEVERAL MORE HOURS. 
   OVER SABINE RIVER REGION...SFC COOLING WILL BE MORE GRADUAL GIVEN
   DEW POINTS NEAR 70 F...WITH MLCINH UNDER 50 J/KG.  VERTICAL WIND
   PROFILES WILL REMAIN FAVORABLE WITH 45-50 KT EFFECTIVE SHEAR
   MAGNITUDES.  BLEND OF POE VWP...LDB PROFILER AND RUC FCST WINDS
   SUGGESTS LLJ ENHANCEMENT WILL LEAD TO 0-1 KM SRH 300-400 J/KG FOR
   ANY CONVECTION THAT CAN PERSIST INTO JAS/POE REGION.  TSTM
   DEVELOPMENT STILL IS POSSIBLE ALONG DRYLINE NEAR I-35...AND COLD
   FRONT INTERACTING WITH IT FROM N-S...HOWEVER STRENGTHENING MLCINH
   APPEARS TO BE REDUCING PROBABILITY OF SUCH ADDITIONAL DEVELOPMENT
   WITH TIME.
   
   ..EDWARDS.. 04/26/2011
   
   
   ATTN...WFO...LCH...SHV...HGX...FWD...
   
   LAT...LON   32109336 31829317 30829335 30539487 30639603 31599719
               32649667 33339564 32789501 32109336