SEL2
   
   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 42
   NWS STORM PREDICTION CENTER NORMAN OK
   210 PM CDT SUN APR 4 2004
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          SOUTHWEST TEXAS
   
   EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 210 PM UNTIL 800
   PM CDT.
   
   HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
   MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
   
   THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 50 STATUTE MILES
   EITHER SIDE OF A LINE FROM 125 MILES WEST SOUTHWEST OF SANDERSON
   TEXAS TO 50 MILES EAST NORTHEAST OF SANDERSON TEXAS.
   
   REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
   FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
   PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
   WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
   WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
   TORNADOES.
   
   
   OTHER WATCH INFORMATION...CONTINUE...WW 41...
   
   
   DISCUSSION...THUNDERSTORMS ARE STARTING TO DEVELOP OVER THE
   MOUNTAINS OF SWRN TX AND ADJACENT PARTS OF NRN MEXICO AS DIURNAL
   HEATING AND DYNAMIC FORCING ASSOCIATED WITH SRN END OF NRN MEXICO
   SHORT WAVE TROUGH ENHANCE UPWARD MOTION.  VISIBLE IMAGERY SHOWS
   REGIONS OF ENHANCED HEATING/DESTABILIZATION OVER THE BIG BEND
   AREA...WITH MUCAPE OF 1000-2000 J/KG BASED ON HOURLY RUC DATA. 
   OUTFLOW BOUNDARY MOVING SEWD FROM FST-MRF IS EXPECTED TO ENHANCE LOW
   LEVEL CONVERGENCE AND AID IN DEVELOPMENT OF NEW STORMS.  STRONG
   VERTICAL SHEAR RESULTING FROM SELY LOW LEVEL FLOW VEERING TO SWLY
   ALOFT WILL SUPPORT STRONG/SEVERE STORM DEVELOPMENT THROUGH THE
   EVENING HOURS.
   
   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
   MOTION VECTOR 22030.
   
   
   ...WEISS