SEL8
   
   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 208
   NWS STORM PREDICTION CENTER NORMAN OK
   345 PM CDT THU APR 28 2005
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          NORTHERN AND WESTERN ARKANSAS
          SOUTHERN MISSOURI
          EXTREME EAST CENTRAL OKLAHOMA
   
   EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 345 PM UNTIL
   1000 PM CDT.
   
   HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 60
   MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
   
   THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 80
   STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTHWEST OF
   WEST PLAINS MISSOURI TO 45 MILES SOUTH SOUTHEAST OF FORT SMITH
   ARKANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).
   
   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.
   
   DISCUSSION...CONVERGENCE...ALONG A SLOW MOVING COLD FRONT IN ERN OK
   AND A WARM FRONT THAT EXTENDS FROM NEAR MKO TO NEAR LIT...IS
   EXPECTED TO INCREASE AS EXIT REGION OF UPPER LEVEL SPEED MAX MOVES
   INTO THE AREA FROM WRN OK. MUCAPES HAVE INCREASED TO NEAR 1500 J/KG
   AND DEEP LAYER SHEAR NEAR 60 KT WILL BE SUFFICIENT FOR SUPERCELLS.
   EXPECT STORMS TO DEVELOP DURING THE NEXT HOUR OR SO AND THEN RAPIDLY
   INTENSIFY DURING THE EVENING HOURS. RELATIVELY HIGH LFC/S IN THE
   WARM SECTOR SUGGEST THAT WIND DAMAGE AND HAIL WILL BE THE MAIN
   THREATS NEAR THE SURFACE FRONT WITH HAIL MOST LIKELY NORTH OF THE
   WARM FRONT.
   
   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 50
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400. MEAN STORM
   MOTION VECTOR 25035.
   
   
   ...IMY