MESOSCALE DISCUSSION 0500
   NWS STORM PREDICTION CENTER NORMAN OK
   1215 PM CDT SAT APR 19 2003
   
   AREAS AFFECTED...PORTIONS ERN IA...NRN/WRN IL..EXTREME SWRN WI
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 191715Z - 191945Z
   
   SCATTERED TSTMS WILL MOVE NEWD ACROSS DISCUSSION AREA THROUGH AT
   LEAST 19Z...A FEW OF WHICH MAY INCREASE TO SEVERE LEVELS WITH
   POTENTIAL FOR HAIL...OR BRIEF GUSTS NEAR SEVERE LEVELS.  WW NOT
   ANTICIPATED ATTM BECAUSE OF MARGINALITY AND RELATIVELY SHORT
   DURATION OF THREAT.
   
   AREA OF PRESENTLY ELEVATED TSTMS IS INCREASING IN
   COVERAGE/INTENSITY ACROSS PORTIONS CENTRAL/WRN IL AND NERN
   MO...AND IS MOVING INTO SERN IA.  SOME OF THIS ACTIVITY MAY
   BECOME SFC BASED BEFORE LIFTING NWD OVER WARM FRONT -- NOW
   ANALYZED FROM CHI AREA WNWWD TOWARD ALO.  SOME ENHANCEMENT TO
   VERTICAL SHEAR AND LARGE SCALE ASCENT IS ANTICIPATED OVER THIS
   REGION BECAUSE OF APPARENT CONVECTIVELY INDUCED VORTEX NOW
   LIFTING NEWD ACROSS NWRN MO.  LOW LEVEL THETAE ADVECTION COMBINED
   WITH POCKET OF INSOLATION N OF PRECIP SHIELD HAS RAISED
   TEMPERATURES OVER PORTIONS ERN IA TO NEAR 70 F...WHICH YIELDS
   200-500 J/KG SBCAPE.  VERTICAL SHEAR PROFILES SUPPORT ORGANIZED
   TSTMS WITH INTERMITTENT MIDLEVEL ROTATION...GIVEN 40-50 KT
   DEEP-LAYER SHEAR AND NEARLY UNIDIRECTIONAL WIND PROFILES
   EXPECTED.  LACK OF MORE SUBSTANTIAL DESTABILIZATION WILL LIMIT
   OVERALL SEVERE TSTM HAZARD.
   
   ..EDWARDS.. 04/19/2003
   
   
   ATTN...WFO...LOT...ILX...MKX...DVN...ARX...DMX...
   
   40458948 41119323 42819232 42388909