MESOSCALE DISCUSSION 0778
   NWS STORM PREDICTION CENTER NORMAN OK
   0454 PM CDT THU MAY 20 2004
   
   AREAS AFFECTED...SRN IA
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 202154Z - 202330Z
   
   ISOLATED STRONG-SEVERE STORMS SHOULD CONTINUE TO DEVELOP ACROSS SRN
   IA. SUPERCELLS WILL BE LIKELY WITH LARGE HAIL AND DAMAGING WINDS
   POSSIBLE. A NEW WW WILL BE ISSUED SHORTLY.
   
   SFC ANALYSIS SHOWS A COLD FRONT EXTENDING NE TO SW FROM CNTRL WI
   THROUGH CNTRL IA INTO NE KS. A CAP IS IN PLACE ACROSS THE REGION BUT
   LOW-LEVEL CONVERGENCE HAS INCREASED ALONG THE FRONT WHICH IS
   ALLOWING THE CONVECTION TO BREAK THE CAP. AS A RESULT... SCATTERED
   STORMS SHOULD CONTINUE TO DEVELOP OVER THE NEXT HOUR OR TWO. A
   MODIFIED 18Z SOUNDING FROM DVN SHOWS 35 KT OF 0-6 KM SHEAR WITH 4500
    J/KG OF MLCAPE SUGGESTING SUPERCELLS WILL BE LIKELY. ALTHOUGH
   LOW-LEVEL SHEAR IS WEAK...OBJECTIVE ANALYSIS SHOWS LCLS BELOW 1200
   METERS ACROSS SRN IA. THIS COUPLED WITH VERY UNSTABLE AIR AND
   MODERATE DEEP LAYER SHEAR SHOULD BE ENOUGH FOR A TORNADO THREAT
   ACROSS SCNTRL AND SWRN IA. LARGE HAIL AND DAMAGING WINDS WILL ALSO
   BE POSSIBLE WITH THE STRONGER STORMS.
   
   ..BROYLES.. 05/20/2004
   
   
   ATTN...WFO...DVN...DMX...EAX...OAX...
   
   40939168 40729207 40539292 40419399 40379523 40779573
   41269572 42079448 42199249 41999167 41389151