MESOSCALE DISCUSSION 0395
   NWS STORM PREDICTION CENTER NORMAN OK
   0546 PM CDT TUE APR 20 2004
   
   AREAS AFFECTED...PORTIONS S-CENTRAL/SERN OK...N-CENTRAL TX
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 202246Z - 210015Z
   
   CONVECTION MAY BREAK CAP INVOF DRYLINE OVER THIS REGION AND MOVE
   ENEWD...BECOMING ISOLATED SUPERCELLS.  WE ARE MONITORING CONVECTIVE
   TRENDS FOR POSSIBLE WW.
   
   18Z FWD RAOB INDICATED STRONG CAP ACROSS THIS REGION...AND
   MODIFICATIONS FOR 22Z TEMPS/DEW POINTS ACROSS REGION STILL LEAVE
   AROUND 100 J/KG CINH.  HOWEVER....MIDLEVEL COOLING AHEAD OF STRONG
   TROUGH ALOFT...AND BOUNDARY LAYER ASCENT INVOF DRYLINE...CONTRIBUTE
   TO MUCH WEAKER CAPPING IN MODIFIED RUC SOUNDINGS FOR NEXT 1-2 HOURS.
    1500-2000 J/KG MLCAPE IS EVIDENT PER MODIFIED RUC SOUNDINGS ALONG
   WITH LCL AROUND 5 KFT AGL.  22Z VIS IMAGERY SHOWS SEVERAL TCU WITHIN
   BAND EXTENDING FROM CARTER COUNTY OK SWWD TO JACK/WISE COUNTIES TX. 
   ANY SUSTAINED DEEP CONVECTION SHOULD ROTATE WITH 150-250 J/KG SRH
   EVIDENT ON PRC PROFILER AND FWD VWP ANALYSIS.  MOST PROBABLE TIME
   FOR CAP TO BREAK IS BEFORE 02Z.  THEREAFTER DIABATIC BOUNDARY LAYER
   COOLING SHOULD PRECLUDE NEW FORMATION OF SFC-BASED CONVECTION.
   
   ..EDWARDS.. 04/20/2004
   
   
   ATTN...WFO...TSA...FWD...OUN...
   
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