MESO: Mesoscale Discussion 1198

ACUS11 KWNS 171915
SWOMCD
SPC MCD 171915
MNZ000-SDZ000-NDZ000-172115-

MESOSCALE DISCUSSION 1198
NWS STORM PREDICTION CENTER NORMAN OK
0215 PM CDT SUN JUN 17 2012

AREAS AFFECTED...NERN SD...SWRN MN AND SERN ND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 171915Z - 172115Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...SEVERE STORMS ARE EXPECTED TO DEVELOP FROM NERN SD INTO
SWRN MN THIS AFTERNOON...MOST LIKELY BETWEEN 20-22Z. SUPERCELLS WITH
VERY LARGE HAIL WILL BE THE INITIAL PRIMARY THREAT...ALONG WITH A
THREAT FOR ISOLATED TORNADOES. STORMS SHOULD EVENTUALLY GROW UPSCALE
INTO LINES AND OR CLUSTERS WITH AN INCREASING THREAT FOR DAMAGING
WIND.

DISCUSSION...THIS AFTERNOON A WARM FRONT STRETCHES FROM WRN IA NWWD
TO EXTREME SERN MN...NERN SD TO A SFC LOW IN SCNTRL ND. TROUGH AXIS
EXTENDS SWD THROUGH WCNTRL SD. AN E-W CONVECTIVE OUTFLOW BOUNDARY
WAS ALSO INDICATED OVER SWRN MN WWD INTO EXTREME ERN SD JUST NORTH
OF SIOUX FALLS. WARM SECTOR HAS BEEN DESTABILIZING WHERE PLUME OF
7.5 C/KM MID LEVEL LAPSE RATES HAVE ADVECTED ABOVE MID 60S DEWPOINTS
WITH 2000-2500 J/KG MLCAPE INDICATED OVER ERN SD. THE EWD ADVECTING
EML HAS CAPPED THE BOUNDARY LAYER AND INHIBITED SURFACE BASED
CONVECTIVE INITIATION SO FAR. HOWEVER...AS THE SFC LAYER CONTINUES
TO WARM...STORMS ARE EXPECTED TO DEVELOP MOST LIKELY WITHIN ZONE OF
ENHANCED CONVERGENCE WHERE THE LLJ INTERSECTS WRN EXTENSION OF
OUTFLOW BOUNDARY OVER SWRN MN AND FAR ERN SD. OTHER STORMS MAY
DEVELOP FARTHER NORTH FROM SRN ND INTO NRN SD ALONG AND EAST OF SFC
TROUGH/DRYLINE AND WITHIN ZONE OF HEIGHT FALLS ASSOCIATED WITH
PROGRESSIVE VORT MAX LOCATED OVER EXTREME SRN ALBERTA. VERTICAL
SHEAR OF 40+ KT WILL SUPPORT ORGANIZED STORMS INCLUDING SUPERCELLS.
TORNADO THREAT WILL BE GREATEST FROM NERN SD INTO SWRN MN ALONG NOSE
OF LLJ AND WHERE SLIGHTLY LOWER LCLS EXIST ALONG MOIST AXIS AND
WHERE THE BOUNDARY LAYER IS COOLER. STORMS MAY EVENTUALLY EVOLVE
INTO CLUSTERS AND LINES WITH A CONTINUING THREAT OF DAMAGING WIND
AND LARGE HAIL INTO THE EARLY EVENING.

..DIAL/HART.. 06/17/2012

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

ATTN...WFO...MPX...FGF...FSD...ABR...BIS...

LAT...LON 44149617 44729750 46169949 46659716 45919543 44479525
44149617

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