MESOSCALE DISCUSSION 0501
   NWS STORM PREDICTION CENTER NORMAN OK
   0110 PM CDT SAT APR 19 2003
   
   AREAS AFFECTED...PORTIONS NRN/CENTRAL OK AND SRN KS
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 191810Z - 192015Z
   
   TSTM DEVELOPMENT POSSIBLE OVER PORTIONS NWRN AND CENTRAL OK
   THROUGH 21Z...BUILDING EWD/SEWD IN AN ARC.  ACTIVITY IS EXPECTED
   TO BECOME SEVERE QUICKLY AS IT LIFTS NEWD ACROSS REMAINDER
   CENTRAL/NRN OK AND PORTIONS SRN KS.  OVER NWRN OK AND
   SWRN/S--CENTRAL KS...LOW-TOPPED SUPERCELLS ARE POSSIBLE WITH
   TORNADOES AND LARGE HAIL.  GIVEN CURVING SPATIAL ORIENTATION OF
   THREAT...TORNADO WW WILL BE ISSUED SHORTLY OVER PORTIONS NRN
   OK/SRN KS...AND ADDITIONAL WW MAY BE REQUIRED WITHIN AN HOUR OR
   TWO FARTHER SE.
   
   SFC MESOANALYSIS SHOWS COLD FRONT FROM NEAR EMP WSWWD INTO ERN OK
   PANHANDLE...AND DRYLINE MIXING AND ADVECTING EWD ACROSS
   W-CENTRAL/SWRN OK AND NERN TX PANHANDLE.  BY 20Z...EXPECT DRYLINE
   TO REACH AT LEAST AS FAR E AS CURRENTLY ANALYZED CONFLUENCE LINE
   FROM DFW METROPLEX NNWWD ACROSS GRADY COUNTY OK TO NEAR
   GAG...THEN MOVE NEWD ACROSS DISCUSSION AREA THEREAFTER.  SMALL
   ARC OF CU ALREADY EVIDENT ON VIS IMAGERY OVER NERN TX PANHANDLE
   SEWD TO ROGER MILLS COUNTY OK.
   
   LARGE SCALE ASCENT AND VERTICAL SHEAR ARE INCREASING ACROSS SWRN
   KS/NWRN OK ATTM...AS EVIDENT BY ELEVATED TSTMS INCREASING N OF
   COLD FRONT OVER SWRN KS.  THIS REGIME SHOULD EXPAND EWD ACROSS
   MORE OF CENTRAL/NRN OK AS MID-UPPER CYCLONE AND ASSOCIATED SPEED
   MAX ALOFT MOVES NEWD.  ASSOCIATED DESTABILIZATION WILL COOL
   MIDLEVEL TEMPERATURES CONSIDERABLY.  ACCORDINGLY...VERY STEEP
   LOW-MIDLEVEL LAPSE RATES NEAR 9 DEG C/KM WILL SUPPORT NEAR 2000
   J/KG MLCAPE IN NWRN OK...2500 J/KG OVER CENTRAL OK. 
   FURTHERMORE...EXPECT MAX LI AS LOW AS -20 AND HIGH CAPE DENSITY
   GIVEN SHALLOWNESS OF TROPOSPHERE -- LEADING TO EXCEPTIONALLY
   INTENSE VERTICAL UPDRAFT ACCELERATIONS.  WHEN COMBINED WITH
   EXPECTED STORM ROTATION...ASSOCIATED STRETCHING SHOULD AID
   TORNADO POTENTIAL AND HELP TO OFFSET SOME SR FLOW WEAKNESSES
   EVIDENT ATOP BOUNDARY LAYER IN LMN/VCI PROFILERS...VNX VWP
   PRODUCT AND RUC FORECAST SOUNDINGS.   VERTICAL SHEAR PROFILES
   WILL BE FAVORABLE FOR SUPERCELLS WITH 0-3 KM SRH 200-400 J/KG AND
   0-6 KM AGL SHEAR AS HIGH AS 85 KT.  
   
   ..EDWARDS.. 04/19/2003
   
   
   ATTN...WFO...TSA...ICT...OUN...DDC...AMA...
   
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