MESOSCALE DISCUSSION 0251
   NWS STORM PREDICTION CENTER NORMAN OK
   0800 PM CDT TUE MAR 22 2011
   
   AREAS AFFECTED...SERN IA...NERN MO AND W-CNTRL IL
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 230100Z - 230200Z
   
   THREAT FOR SEVERE STORMS COULD SHIFT INTO SERN IA...NERN MO AND
   POSSIBLY W-CNTRL IL THIS EVENING. WW 53 WILL LIKELY NEED TO BE
   REPLACED BY ANOTHER WW BEFORE 02Z. HOWEVER...OVERALL SEVERE THREAT
   DOES NOT APPEAR AS GREAT AS EARLIER THIS EVENING. 
   
   TREND HAS BEEN FOR STORMS TO EVOLVE INTO LINES ACROSS S-CNTRL IA AS
   COLD FRONT OVERTAKES THE DRYLINE...AND SOME SWD DEVELOPMENT INTO NRN
   MO IS POSSIBLE AS THIS PROCESS CONTINUES. DISCRETE SUPERCELLS IN
   WARM SECTOR HAVE WEAKENED AS THE BOUNDARY LAYER STABILIZES AND
   STORMS CROSS ONTO THE COOL SIDE OF WARM FRONT. SURFACE HIGH PRESSURE
   ANCHORED OVER SERN CANADA EXTENDING INTO THE GREAT LAKES WILL TEND
   TO INHIBIT NWD PROGRESSION OF WARM FRONT CURRENTLY EXTENDING ACROSS
   SRN IA. INSTABILITY DECREASES WITH ERN EXTENT THROUGH WARM SECTOR
   ACROSS SERN IA...NERN MO AND W-CNTRL IL DUE TO WIDESPREAD CLOUDS
   EARLIER TODAY. WITH ONSET OF NOCTURNAL COOLING...BOUNDARY LAYER WILL
   LIKELY REMAIN RELATIVELY STABLE...AND THIS SHOULD SERVE AS A
   LIMITING FACTOR FOR A MORE ROBUST SEVERE THREAT. 
   
   NEVERTHELESS...FORCING ASSOCIATED WITH NEWD EJECTING VORT MAX AND
   ATTENDANT COLD FRONT MAY BE SUFFICIENT TO MAINTAIN LINE OF STORMS
   THROUGH SERN IA AND NERN MO NEXT FEW HOURS. STORMS WILL REMAIN
   EMBEDDED WITHIN STRONG VERTICAL SHEAR SUPPORTIVE OF SUPERCELLS AND
   BOWING SEGMENTS. WHILE AN ISOLATED TORNADO OR TWO CANNOT BE RULED
   OUT...SEVERE THREAT APPEARS TO BE TRANSITIONING TO ISOLATED DAMAGING
   WIND AND HAIL.
   
   ..DIAL.. 03/23/2011
   
   
   ATTN...WFO...LSX...DVN...DMX...EAX...
   
   LAT...LON   40519105 39749280 39939394 41629261 41329078 40519105