MESO: Mesoscale Discussion 1206

ACUS11 KWNS 181641
SWOMCD
SPC MCD 181640
MIZ000-WIZ000-MNZ000-181845-

MESOSCALE DISCUSSION 1206
NWS STORM PREDICTION CENTER NORMAN OK
1140 AM CDT MON JUN 18 2012

AREAS AFFECTED...CNTRL/NERN WI...ERN UPPER MI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 181640Z - 181845Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...SEVERE POTENTIAL WILL INCREASE WITH BOTH A CLUSTER OF
TSTMS ALONG THE WI/MI BORDER AND ADDITIONAL TSTMS LIKELY FORMING
ALONG A SW/NE-ORIENTED PRE-FRONTAL CONFLUENCE BAND. DEEP-LAYER SHEAR
WILL BE HIGHLY FAVORABLE FOR INITIAL SUPERCELLS AND EVENTUAL UPSCALE
GROWTH INTO AN MCS WITH BOWING SEGMENTS.

DISCUSSION...CU HAS INCREASED ALONG A PRE-FRONTAL CONFLUENCE BAND
SEEN IN VISIBLE SATELLITE IMAGERY FROM AROUND 30 S MSP TO 45 NE EAU
IN THE WAKE OF PROBABLE ELEVATED CONVECTION ALONG THE WI/MI BORDER.
AIR MASS IS STRONGLY DESTABILIZING IN BETWEEN THESE TWO FEATURES
WITH MLCAPE NEARING 2000 J/KG AND WEAKENING MLCIN. GIVEN THE DEGREE
OF INSTABILITY IN WI...IT APPEARS LIKELY THAT AT LEAST ISOLATED
TSTMS SHOULD FORM ALONG THE CONFLUENCE BAND BY 18-19Z. WITH 50-60 KT
EFFECTIVE SHEAR AND DEEP-LAYER FLOW LARGELY PARALLELING THE
INITIATING BOUNDARY...INITIAL SUPERCELLS SHOULD QUICKLY GROW UPSCALE
WITH EMBEDDED BOWING STRUCTURES. ALTHOUGH LOW-LEVEL FLOW IS LARGELY
VEERED IN THE WARM SECTOR...AN ISOLATED TORNADO OR TWO IS POSSIBLE
IN NERN WI WHERE FLOW SHOULD REMAIN MORE BACKED. OTHERWISE...SEVERE
WIND/HAIL WILL BE THE PRIMARY RISKS.

..GRAMS/HART.. 06/18/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MQT...GRB...MKX...DLH...ARX...MPX...

LAT...LON 44869150 45448996 45928836 46028746 46048668 45668641
44848712 44238751 43738809 43528948 43609085 43809139
44349194 44869150

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