MESOSCALE DISCUSSION 0627
   NWS STORM PREDICTION CENTER NORMAN OK
   0123 PM CDT THU APR 21 2005
   
   AREAS AFFECTED...SWRN MO...NWRN  AR...NERN OK
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 211823Z - 211930Z
   
   ...SEVERE THUNDERSTORM WATCH WILL BE ISSUED SOON FOR PORTIONS OF
   SWRN/CNTRL MO...NWRN AR...NERN OK...
   
   LOW LEVEL WARM ADVECTION APPEARS RESPONSIBLE FOR RECENT INCREASE IN
   SHOWERS-ISOLATED THUNDERSTORMS ACROSS NERN OK. THIS ACTIVITY SHOULD
   CONTINUE TO INCREASE IN INTENSITY AS BOUNDARY LAYER
   WARMS/DESTABILIZED DOWNSTREAM ACROSS SWRN MO/NWRN AR.  ALTHOUGH
   VERTICAL SHEAR IS NOT PARTICULARLY STRONG...SUFFICIENT VEERING
   THROUGH A DEEP LAYER ON 18Z SGF SOUNDING DOES SUGGEST SOME
   ORGANIZATIONAL POTENTIAL...ESPECIALLY GIVEN THE MODERATE
   INSTABILITY.  SEVERE THUNDERSTORM WATCH WILL BE ISSUED SOON TO
   ADDRESS THIS DEVELOPING SCENARIO.
   
   ..DARROW.. 04/21/2005
   
   
   ATTN...WFO...LSX...LZK...SGF...EAX...TSA...
   
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