MESOSCALE DISCUSSION 0400
   NWS STORM PREDICTION CENTER NORMAN OK
   0425 PM CDT SAT MAR 31 2007
   
   AREAS AFFECTED...NORTHERN/CENTRAL IL AND FAR SOUTHERN WI
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 312125Z - 312330Z
   
   WITH A SEVERE THREAT EXPECTED TO INCREASE BY EARLY EVENING...WILL
   CLOSELY MONITOR FOR THE POSSIBILITY OF A WATCH INTO NORTHERN/CENTRAL
   IL AND PERHAPS FAR SOUTHERN WI OVER THE NEXT HOUR OR TWO.
   
   SURFACE ANALYSIS TRENDS DEPICT WARM FRONT GRADUALLY LIFTING
   NORTHWARD ACROSS EAST CENTRAL IA AND NORTH CENTRAL IL AT LATE
   AFTERNOON...WHILE PACIFIC COLD FRONT ADVANCES EASTWARD ACROSS
   CENTRAL MO. EAST OF TORNADO WATCH 101 FOR IA/WEST CENTRAL IL...THE
   AIRMASS HAS ONLY MODESTLY DESTABILIZED THUS FAR ACROSS MUCH OF
   NORTHERN/CENTRAL IL...LARGELY OWING TO WIDESPREAD CLOUD COVER.
   ALTHOUGH CONVECTIVE INHIBITION CONTINUES TO GRADUALLY
   ERODE...MODIFIED 18Z DAVENPORT IA/12Z LINCOLN IL RAOBS SUGGEST
   MLCAPES ARE LESS THAN 500 J/KG ACROSS IL.
   
   AS LARGE SCALE FORCING FOR ASCENT OVERSPREADS THE REGION THIS
   EVENING...A SEVERE THREAT WILL LIKELY INCREASE ACROSS
   NORTHERN/CENTRAL IL AND PERHAPS SOUTHWEST/SOUTH CENTRAL WI THIS
   EVENING. THIS WOULD BE THE CASE WITH STORMS DEVELOPING NEAR/JUST
   NORTH OF THE WARM FRONT ACROSS NORTH CENTRAL IL...AND MORE
   LIKELY...A DOWNSTREAM SPREAD OF STRONG/SEVERE STORMS INTO IL/FAR
   SOUTHERN WI ASSOCIATED WITH THE PACIFIC COLD FRONT ADVANCING INTO
   IL. CONSISTENT WITH REGIONAL PROFILER TRENDS FROM CONWAY
   MO/WINCHESTER IL...LATEST RUC GUIDANCE SUGGESTS A SOUTHERLY 50+ KT
   LOW LEVEL JET WILL INCREASE EARLY THIS EVENING ACROSS IL. EVEN IN AN
   ENVIRONMENT CHARACTERIZED BY MODEST BUOYANCY...THE THREAT FOR
   ROTATING STORMS/DAMAGING WIND GUSTS WILL EXIST GIVEN THE
   INCREASINGLY STRONG WIND FIELDS THIS EVENING. IN ADDITION TO
   DAMAGING WINDS/SOME HAIL...THE POSSIBILITY FOR AN ISOLATED TORNADO
   OR TWO WILL EXIST...ESPECIALLY NEAR THE WARM FRONT WHERE LOW LEVEL
   HELICITY IS MAXIMIZED.
   
   ..GUYER.. 03/31/2007
   
   
   ATTN...WFO...LOT...ILX...MKX...LSX...DVN...ARX...
   
   43029063 43118961 42568839 41188771 40168784 39308856
   39208956 39509020 40639030 41829008