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Mesoscale Discussion 1394
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   MESOSCALE DISCUSSION 1394
   NWS STORM PREDICTION CENTER NORMAN OK
   0321 PM CDT MON JUL 13 2015

   AREAS AFFECTED...NRN/CNTRL IL...FAR SRN WI

   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   VALID 132021Z - 132145Z

   CORRECTED FOR INCORRECT GEOGRAPHIC REFERENCE

   PROBABILITY OF WATCH ISSUANCE...95 PERCENT

   SUMMARY...EXPLOSIVE TSTM DEVELOPMENT IS POSSIBLE WITHIN THE NEXT TWO
   HOURS ACROSS FAR SRN WI AND NRN IL WITH ALL SEVERE HAZARDS POSSIBLE
   INITIALLY. A SIGNIFICANT WIND THREAT IS THEN EXPECTED TO DEVELOP
   DOWNSTREAM ACROSS NRN/CNTRL IL. WW ISSUANCE IS LIKELY.

   DISCUSSION...18Z SOUNDINGS FROM DVN AND AND ILX SAMPLED STEEP
   MID-LEVEL LAPSE RATES ATOP WARM AND VERY MOIST SURFACE
   CONDITIONS...RESULTING IN EXTREME INSTABILITY WITH MLCAPE OF 3100
   AND 4300 J PER KG...RESPECTIVELY. UPDATING THE ILX 18Z SOUNDING WITH
   CURRENT SURFACE OBSERVATIONS PUSHES THE MLCAPE OVER 5000 J PER KG AT
   ILX WITH LESS THAN 20 J PER KG OF MLCINH REMAINING. THESE SOUNDINGS
   ALSO SAMPLED A STRONGLY SHEARED ENVIRONMENT WITH 0-6 KM BULK SHEAR
   OF 54 KT AND EFFECTIVE SHEAR OF 66 KT REPORTED AT ILX. 

   SURFACE ANALYSIS REVEALS THE OUTFLOW BOUNDARY FROM THIS MORNING/S
   MCS IS NOW EFFECTIVELY A WARM FRONT WHICH EXTENDS FROM LWV ALONG THE
   SRN IL/IND BORDER NWWD TO A SURFACE LOW JUST SE OF LSE IN SW WI. AS
   NOTED IN THE SOUNDING ANALYSIS ABOVE...AIRMASS ALONG AND SW OF THIS
   BOUNDARY IS EXTREMELY UNSTABLE. RECENT VISIBLE SATELLITE DEPICTS AN
   INCREASING CU FIELD ACROSS THE REGION BUT MOST OF THE CU STILL HAS A
   SOMEWHAT FLAT APPEARANCE...SUGGESTING CONVECTIVE INHIBITION HAS NOT
   COMPLETELY ERODED YET. 

   CONTINUED DESTABILIZATION IS EXPECTED TO CONTINUE WITH THE MOST
   LIKELY LOCATION FOR EVENTUAL CONVECTIVE INITIATION ACROSS FAR SRN WI
   AND/OR NRN IL. GIVEN THE OVERALL THERMODYNAMIC AND KINEMATIC
   ENVIRONMENT...EXPLOSIVE TSTM DEVELOPMENT IS EXPECTED ONCE CONVECTIVE
   INITIATION OCCURS WITH ALL SEVERE HAZARDS POSSIBLE. THE EXPECTED
   ORIENTATION OF THE STORMS SUGGESTS QUICK UPSCALE GROWTH IS PROBABLE
   WITH A SIGNIFICANT THREAT FOR DAMAGING WINDS DOWNSTREAM ACROSS
   NRN/NE IL INTO CNTRL IL.

   ..MOSIER/HART.. 07/13/2015


   ATTN...WFO...LOT...ILX...MKX...DVN...ARX...

   LAT...LON   42858866 42658833 42458809 41818790 40258773 39738782
               39708826 40148966 40509000 40949024 41509044 41859056
               42579056 42989022 43068962 42948894 42858866 

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Page last modified: July 13, 2015
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