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Mesoscale Discussion 1219
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   MESOSCALE DISCUSSION 1219
   NWS STORM PREDICTION CENTER NORMAN OK
   1243 PM CDT TUE JUN 25 2013

   AREAS AFFECTED...E-CNTRL/NERN MO...A LARGE PART OF IL...PARTS OF FAR
   ERN IA...PARTS OF FAR WRN INDIANA

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 251743Z - 252015Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...THUNDERSTORMS WILL LIKELY INCREASE IN COVERAGE AND
   INTENSITY THROUGH THE AFTERNOON HOURS...AND MAY PRODUCE SVR WIND
   GUSTS AND HAIL. THE AREA IS BEING MONITORED FOR POSSIBLE SVR TSTM
   WATCH ISSUANCE.

   DISCUSSION...EARLY AFTERNOON SFC MESOANALYSIS HIGHLIGHTS A COUPLE OF
   SFC FEATURES THAT WILL POTENTIALLY SERVE AS FOCI FOR INITIAL
   THUNDERSTORM DEVELOPMENT THIS AFTERNOON:
   /1/ AN OUTFLOW BOUNDARY ARCING FROM NRN IL INTO E-CNTRL IA DEPOSITED
   BY A CONVECTIVE CLUSTER WHICH MOVED ACROSS THAT GENERAL AREA EARLIER
   TODAY...AND
   /2/ A DIFFERENTIAL HEATING ZONE OVER THE FRINGES OF MULTI-LAYERED
   CONVECTIVE CLOUD DEBRIS EXTENDING APPROXIMATELY W/E THROUGH CNTRL IL
   AND NE/SW IN NERN/CNTRL MO. INITIAL CELL DEVELOPMENT HAS ALREADY
   BEEN NOTED IN LOGAN COUNTY IL INVOF THE DIFFERENTIAL HEATING ZONE.

   MODIFICATIONS TO THE ILX 12Z RAOB FOR SFC CONDITIONS S OF THE
   OUTFLOW BOUNDARY SUGGEST MLCAPE HAS INCREASED TO AROUND 3000-3500
   J/KG WITH VERY LITTLE MLCINH. CONTINUED DIABATIC SFC HEATING AMIDST
   RICH LOW-LEVEL MOISTURE -- E.G. LOWEST 100-MB MEAN MIXING RATIO
   AROUND 16.5 G/KG PER 12Z ILX RAOB -- BENEATH THE NEWD EXTENT OF AN
   EML FEATURING 7-8-C/KM MID-LEVEL LAPSE RATES SHOULD YIELD A VERY
   UNSTABLE AIR MASS THROUGH THE AFTERNOON.

   PRESENT INDICATIONS ARE THAT CONVECTION WILL INCREASE IN
   COVERAGE/INTENSITY THROUGH THE AFTERNOON...WHILE WEAK WAA
   ACCOMPANYING A 20-30-KT LOW-LEVEL JET MAX PERSISTS. THE
   AFOREMENTIONED DEGREE OF BUOYANCY SHOULD SUPPORT VIGOROUS
   UPDRAFTS/DOWNDRAFTS...CAPABLE OF DMGG WINDS GUSTS AND SVR HAIL. WITH
   25-35 KT OF EFFECTIVE BULK SHEAR -- HIGHEST N OF INTERSTATE 70 -- A
   FEW ORGANIZED STORM STRUCTURES/SMALL CONVECTIVE CLUSTERS MAY ENSUE.
   THERE IS SOME QUESTION REGARDING THE ANTICIPATED COVERAGE OF SVR
   CONVECTION...HOWEVER...AS DEEP-LAYER FORCING FOR ASCENT SHOULD BE
   LIMITED. REGARDLESS...THE AREA WILL BE MONITORED FOR THE POSSIBLE
   ISSUANCE OF A SVR TSTM WATCH THROUGH THE AFTERNOON.

   ..COHEN/KERR.. 06/25/2013


   ATTN...WFO...IND...LOT...ILX...LSX...DVN...SGF...EAX...

   LAT...LON   41279080 41518886 41488749 40438722 39418782 38658890
               38189047 38169215 39019262 41279080 

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