MESOSCALE DISCUSSION 0571
   NWS STORM PREDICTION CENTER NORMAN OK
   0128 PM CDT MON APR 25 2011
   
   AREAS AFFECTED...NORTH-CENTRAL/NORTHEAST TX AND EASTERN OK TO
   AR/NORTHWEST LA
   
   CONCERNING...TORNADO WATCH 201...
   
   VALID 251828Z - 252000Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 201 CONTINUES.
   
   TORNADO WATCH 201 CONTINUES UNTIL 23Z...WITH A RISK OF
   TORNADOES/LARGE HAIL AND DAMAGING WINDS.
   
   A NUMBER OF STRONG/SEVERE TSTMS...WITH A COMPLEX CONVECTIVE
   MODE...CONTINUE TO OCCUR WITHIN A CORRIDOR OF PRE-FRONTAL CONFLUENCE
   FROM NORTHEAST TX INTO SOUTHEAST OK/FAR WESTERN AR...WITH OTHER MORE
   RECENT/SEPARATE DEVELOPMENT BEGINNING TO OCCUR FARTHER WEST NEAR THE
   MERGING COLD FRONT/DRYLINE FORM SOUTH-CENTRAL OK INTO NORTH-CENTRAL
   TX. IN THE WESTERNMOST PORTIONS OF TORNADO WATCH 201...VISIBLE
   SATELLITE/SURFACE OBSERVATIONS REFLECT A NARROW CORRIDOR OF STRONGER
   IMPLIED SURFACE BASED DESTABILIZATION READILY OCCURRING
   ALONG/IMMEDIATELY AHEAD OF AND NEAR THE MERGING SOUTHEAST MOVING
   COLD FRONT/EASTWARD ADVANCING DRYLINE. HERE...MODIFICATIONS OF THE
   12Z DALLAS-FORT WORTH OBSERVED RAOB ARE NOW SUGGESTIVE OF 3500+ J/KG
   OF WEAKLY CAPPED MLCAPE AMID UPPER 60S F SURFACE DEWPOINTS. WITH AN
   INITIALLY MORE ISOLATED/SEMI-DISCRETE INITIATION EXPECTED...THESE
   STORMS MAY PROVIDE THE MOST CONSEQUENTIAL TORNADO/VERY LARGE HAIL
   THREAT THROUGH THE AFTERNOON ACROSS WW 201. 
   
   THAT SAID...ANY STORMS...AHEAD OF THE ENE-ADVANCING OK SURFACE LOW
   AND ALONG/SOUTH OF THE WEST-EAST CONVECTIVELY REINFORCED BOUNDARY
   FROM EAST-CENTRAL OK INTO CENTRAL AR...AND POINTS WEST-SOUTHWARD
   INTO THE WARM SECTOR...MAY POSE A TORNADO THREAT WITH A RELATIVELY
   RICH SRH ENVIRONMENT PER REGIONAL WSR-88D VWPS/PROFILERS.
   
   WITH NORTH EXTENT...SURFACE BASED DESTABILIZATION REMAINS MORE
   UNCERTAIN ACROSS NORTHEAST OK/NORTHERN AR OWING TO CONSIDERABLE
   ONGOING CONVECTION...ALTHOUGH THESE AREAS WILL BE MONITORED FOR
   BOUNDARY LAYER RECOVERY/DESTABILIZATION THROUGH THE AFTERNOON. IN
   SPITE OF THE EXTENSIVE ONGOING CONVECTION...AT LEAST SOME NORTHWARD
   ADVANCEMENT OF THE AFOREMENTIONED WEST-EAST BOUNDARY SEEMS PROBABLE
   AHEAD OF THE SURFACE LOW THIS AFTERNOON/EARLY EVENING.
   
   ..GUYER.. 04/25/2011
   
   
   ATTN...WFO...LZK...SHV...TSA...FWD...OUN...
   
   LAT...LON   31939833 33529824 36149600 35749343 34259363 32439446
               31939833