ACUS11 KWNS 132021
SWOMCD
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
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
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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