SEL4
   
   URGENT - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH NUMBER 104
   NWS STORM PREDICTION CENTER NORMAN OK
   140 PM CDT THU APR 22 2004
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   TORNADO WATCH FOR PORTIONS OF 
   
          WESTERN ARKANSAS
          SOUTHWEST MISSOURI
          EASTERN OKLAHOMA
   
   EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 140 PM UNTIL
   800 PM CDT.
   
   TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
   GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
   AREAS.
   
   THE TORNADO WATCH AREA IS ALONG AND 110 STATUTE MILES EAST AND
   WEST OF A LINE FROM 40 MILES WEST NORTHWEST OF MONETT MISSOURI TO
   45 MILES EAST OF DURANT OKLAHOMA.
   
   REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
   TORNADOES AND 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.
   
   DISCUSSION...BOUNDARY LAYER CONTINUES TO DESTABILIZE WITH HEATING
   NEAR/EAST OF SURFACE LOW/INVERTED SURFACE TROUGH EXTENDING FROM EAST
   CENTRAL OKLAHOMA INTO SOUTHWEST MISSOURI.  LOW-LEVEL WARM ADVECTION
   IS PROVIDING SUPPORT FOR LARGE-SCALE UPWARD VERTICAL MOTION...AND
   WILL CONTRIBUTE TO INTENSE CONVECTIVE DEVELOPMENT IN ENVIRONMENT
   WITH MEAN MIXED LAYER CAPE UP TO 2000 J/KG.  WITH MID-LEVEL CAP SLOW
   TO WEAKEN...DISCRETE SUPERCELLS ARE LIKELY FOR SEVERAL
   HOURS...ENHANCED BY DIFLUENT/DIVERGENT UPPER FLOW...BEFORE STORMS
   INCREASE IN COVERAGE TOWARD EARLY EVENING.  VERY LARGE HAIL/DAMAGING
   WIND GUSTS ARE LIKELY...WITH ISOLATED TORNADOES ALSO POSSIBLE.
   
   AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
   SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
   WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
   500. MEAN STORM MOTION VECTOR 26020.
   
   
   ...KERR