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   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 591
   NWS STORM PREDICTION CENTER NORMAN OK
   130 PM CDT THU JUL 8 2004
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          NORTHWEST ARKANSAS
          EXTREME SOUTHEAST KANSAS
          SOUTHWEST MISSOURI
          NORTHEAST OKLAHOMA
   
   EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 130 PM UNTIL
   700 PM CDT.
   
   HAIL TO 1.5 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 55 STATUTE MILES
   NORTH AND SOUTH OF A LINE FROM 10 MILES NORTH NORTHEAST OF
   SPRINGFIELD MISSOURI TO 35 MILES NORTH NORTHWEST OF MUSKOGEE
   OKLAHOMA.
   
   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...SURFACE-BASED STORMS ARE BEGINNING TO DEVELOP ON THE
   SRN AND ERN FRINGE OF A CONVECTIVE CLUSTER OVER SE KS THAT IS
   ASSOCIATED WITH A CONVECTIVELY INDUCED VORT MAX.  CONTINUED SURFACE
   HEATING WILL WEAKEN CONVECTIVE INHIBITION AND ALLOW ADDITIONAL
   DEVELOPMENT THIS AFTERNOON ACROSS NE OK/SW MO/NW AR...WHERE OUTFLOW
   FROM THE ONGOING CONVECTION ENCOUNTERS STRONG INSTABILITY /MLCAPE
   NEAR 3000 J/KG PER 18Z SGF SOUNDING/.  THE STRONG INSTABILITY AND
   WEAK VERTICAL SHEAR WILL SUPPORT A CLUSTER OF PULSE TYPE SEVERE
   STORMS WITH DAMAGING MICROBURST WINDS AND PERHAPS SOME LARGE HAIL
   THIS AFTERNOON.
   
   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
   MOTION VECTOR 32010.
   
   
   ...THOMPSON