MESOSCALE DISCUSSION 0736
   NWS STORM PREDICTION CENTER NORMAN OK
   1026 AM CDT TUE MAY 18 2004
   
   AREAS AFFECTED...E CNTRL/NE MO INTO CNTRL IL
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 181526Z - 181800Z
   
   CONVECTIVE TRENDS ARE BEING MONITORED. THREAT FOR LARGE HAIL IS
   EXPECTED TO INCREASE BY AROUND 18-19Z...WITH POTENTIAL FOR STRONG
   GUSTY WINDS INCREASING THEREAFTER.  WW MAY BECOME NECESSARY BY EARLY
   AFTERNOON.
   
   AS STRONGER LOW-LEVEL CONVERGENCE/WARM ADVECTION BECOMES FOCUSED
   BENEATH INCREASINGLY CAPPED ENVIRONMENT ACROSS NORTH CENTRAL
   OKLAHOMA/SOUTH CENTRAL KANSAS...ONGOING CONVECTIVE CLUSTER HAS
   WEAKENED AS IT DEVELOPS EASTWARD INTO THE LOWER MISSOURI VALLEY. 
   ACTIVITY IS DEVELOPING EASTWARD WITH FORCING ASSOCIATED WITH WEAK
   MID-LEVEL SHORT WAVE TROUGH/JET STREAK...WHICH MODELS SUGGEST WILL
   SHIFT ACROSS MISSOURI INTO ILLINOIS BY LATE AFTERNOON.
   
   CONVECTION HAS GENERATED FAIRLY SUBSTANTIAL COLD POOL AHEAD OF
   SURFACE COLD FRONT...AND COLD POOL APPEARS TO BE ADVANCING EASTWARD
   AT AROUND 30 KT.  BY/SHORTLY AFTER 18Z...BOUNDARY APPEARS LIKELY TO
   EXTEND EAST OF THE HANNIBAL/QUINCY AREA INTO AREAS NORTH/WEST OF ST.
   LOUIS...WHERE SURFACE TEMPERATURES WILL BE WARMING INTO 80S.  AS
   CAPPING SLOWLY WEAKENS ACROSS THIS AREA...FORCING ALONG LEADING EDGE
   OF CONVECTIVE OUTFLOW LIKELY WILL SUPPORT RE-INTENSIFICATION OF
   VIGOROUS THUNDERSTORM ACTIVITY IN ENVIRONMENT WITH MEAN MIXED LAYER
   CAPE AROUND 1500 J/KG.
   
   THOUGH SHEAR PROFILES NEAR MID-LEVEL JET STREAK WILL BE MODERATE AT
   BEST...SUFFICIENT EVAPORATIVE COOLING SHOULD OCCUR NEAR HEAVIER
   PRECIPITATION CORES TO MAINTAIN FAIRLY STRONG COLD POOL/MESO HIGH. 
   AS SURFACE PRESSURE PERTURBATION STRENGTHENS INTO THE AFTERNOON
   HOURS...RISK OF GUSTY...POTENTIALLY DAMAGING...WINDS LIKELY WILL
   INCREASE ACROSS A LARGE PART OF CENTRAL ILLINOIS.
   
   ..KERR.. 05/18/2004
   
   
   ATTN...WFO...LOT...ILX...LSX...DVN...
   
   39439218 39789134 40489052 41349003 41628886 41348796
   40638758 39128844 38508971 38559128 38589254