MESOSCALE DISCUSSION 0581
   NWS STORM PREDICTION CENTER NORMAN OK
   0900 PM CDT MON APR 29 2013
   
   AREAS AFFECTED...PORTIONS ERN IA...NRN IL...SRN WI.
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 300200Z - 300400Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...ISOLATED/QUICKLY DEVELOPING SVR TSTM PRODUCED 2.5-INCH
   HAIL REPORT NEAR DBQ AT 130Z.  PER COORD W/AFFECTED WFOS...NO WW IS
   BEING ISSUED YET.  HOWEVER...CONVECTIVE TRENDS WILL BE MONITORED FOR
   UPSCALE GROWTH THAT COULD COMPEL WW ISSUANCE...IN ENVIRONMENT THAT
   SHOULD REMAIN FAVORABLE FOR OCNL LARGE HAIL FROM ANY SUSTAINED
   CONVECTION.
   
   DISCUSSION...ACTIVITY NEAR DBQ DEVELOPED NEAR DIFFUSE SFC WARM FRONT
   EXTENDING WNWWD ACROSS SRN MN INTO ERN SD...AND ALSO..NEAR NERN END
   OF FRONTOLYTIC WARM-FRONTAL CORRIDOR THAT EXTENDS INTO LOW OVER
   CENTRAL/SWRN KS.  NEARBY DVN RAOB...IN WARM SECTOR...SAMPLED STEEP
   MIDLEVEL LAPSE RATES AND INCREASING LOW-LEVEL MOISTURE...WITH
   ROUGHLY 1-INCH PW SUPPORTING MLCAPE 800-900 J/KG.  MUCAPE FOR
   INCREASINGLY MOIST PARCELS ROOTED AROUND 800-850 MB IS IN 2000-2500
   J/KG RANGE...MORE REPRESENTATIVE OF RAPID INITIAL INTENSIFICATION
   RATE OF CONVECTION OBSERVED SO FAR.  WITH NEAR-SFC
   COOLING...ACTIVITY SHOULD BE MOSTLY ELEVATED...BUT WITH POTENTIAL TO
   SEND ISOLATED STG/DAMAGING GUST THROUGH SHALLOW NEAR-SFC STABLE
   LAYER.  MAIN CONCERN WILL BE HAIL.
   
   SIGNALS FOR KINEMATIC SUPPORT ARE MIXED...WITH RELATIVELY WEAK
   MID-UPPER WINDS LIMITING CLOUD-LAYER SHEAR.  HOWEVER...LOW-LEVEL WAA
   AND RELATED VEERING OF WINDS WITH HEIGHT CONTRIBUTE TO FAVORABLE
   EFFECTIVE SRH AROUND 200-250 J/KG.  THOUGH FIXED-LAYER SRH SHOULD
   INCREASE BENEATH STRENGTHENING SWLY LLJ...NEAR-SFC DIABATIC
   STABILIZATION WILL EFFECTIVELY TRUNCATE SOME OF THAT HELICITY IN
   VERTICAL.  EFFECTIVE SHEAR MAGNITUDE 35-40 KT IS EXPECTED TO
   CONTINUE.
   
   ..EDWARDS/KERR.. 04/30/2013
   
   
   ATTN...WFO...LOT...MKX...DVN...ARX...DMX...
   
   LAT...LON   43169230 43688963 43558777 43188791 42888782 42768775
               42518782 42168779 41978909 41799056 42089194 43169230