MESOSCALE DISCUSSION 0323
   NWS STORM PREDICTION CENTER NORMAN OK
   1024 AM CDT SAT APR 12 2014

   AREAS AFFECTED...PARTS OF SWRN MN...NE IA...SRN WI...NRN IL...SRN
   LAKE MI AND ADJACENT NW IND/SWRN MI

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 121524Z - 121730Z

   PROBABILITY OF WATCH ISSUANCE...20 PERCENT

   SUMMARY...GUSTY WINDS AND HAIL...PERHAPS LOCALLY APPROACHING OR
   BRIEFLY EXCEEDING SEVERE LIMITS...MAY CONTINUE ANOTHER COUPLE OF
   HOURS WITH SCATTERED STRONGER STORMS ACROSS THE UPPER MIDWEST...SOME
   OF WHICH MAY IMPACT THE CHICAGO METRO AREA BY 18-19Z.

   DISCUSSION...LOWER/MID TROPOSPHERIC WARM ADVECTION ON THE NOSE OF
   WARM ELEVATED MIXED LAYER AIR ADVECTING EAST NORTHEAST OF THE PLAINS
   APPEARS TO BE PROVIDING THE PRIMARY SUPPORT FOR THE ONGOING
   CONVECTIVE DEVELOPMENT ACROSS THE UPPER MIDWEST.  DESPITE SEASONABLY
   WEAK TO MODEST MOISTURE WITHIN THE SOUTHERLY FLOW REGIME TO THE EAST
   OF THE PLAINS SURFACE TROUGH...LATEST OBSERVATIONAL DATA AND
   OBJECTIVE ANALYSIS SUGGEST THAT A LOCAL MAXIMA IN PRECIPITABLE WATER
   /UP TO AROUND 1 INCH/ DOES EXIST TO THE EAST OF A SURFACE LOW CENTER
   NEAR SIOUX FALLS SD.  BENEATH STEEP MID-LEVEL LAPSE RATES THIS
   APPEARS TO BE CONTRIBUTING TO THE DESTABILIZATION SUPPORTING THE
   STRONG/LOCALLY SEVERE STORMS ON THE WESTERN FLANK OF THE CONVECTIVE
   ACTIVITY...WHICH SHOULD CONTINUE TO SPREAD EASTWARD ACROSS
   CENTRAL/SOUTHERN WISCONSIN AND NORTHERN ILLINOIS THROUGH EARLY
   AFTERNOON.

   THE STRONGEST STORMS ALSO APPEAR TO COINCIDE WITH THE MOST
   SUBSTANTIVE MODIFICATION OF THE RESIDUAL COOL/STABLE SURFACE BASED
   AIR MASS WHICH HAS BEEN ENTRENCHED ACROSS PARTS OF THE UPPER GREAT
   LAKES.  THIS MAY BE SLOWER TO OCCUR ACROSS CENTRAL WISCONSIN...WHERE
   SURFACE TEMPERATURES REMAIN IN THE 40S.  

   POTENTIAL FOR STRONGEST STORM DEVELOPMENT...NOW THROUGH 18-19Z...
   SEEMS TO BE WITH STORMS DEVELOPING ALONG THE SURFACE WARM FRONTAL
   ZONE NORTH/EAST OF ROCKFORD IL...TOWARD THE CHICAGO METRO AREA...
   WHERE TEMPERATURES ARE RISING THROUGH THE 60S.  SURFACE DEW POINTS
   REMAIN IN THE LOWER 30S...THOUGH...AND THE INGESTION OF DRIER/MORE
   STABLE AIR STILL SEEMS LIKELY TO EVENTUALLY WEAKEN STORM
   INTENSITIES.

   ..KERR/HART.. 04/12/2014


   ATTN...WFO...GRR...LOT...MKX...DVN...ARX...

   LAT...LON   43939241 44169091 43468865 42928751 42638604 41598764
               42108930 42509046 43489228 43939241