MESO: Mesoscale Discussion 1152

ACUS11 KWNS 131929
SWOMCD
SPC MCD 131928
SDZ000-NDZ000-132030-

MESOSCALE DISCUSSION 1152
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT WED JUN 13 2012

AREAS AFFECTED...WRN SD...SWRN ND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 131928Z - 132030Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...CONVECTIVE INITIATION IS BECOMING INCREASINGLY LIKELY
WITHIN THE NEXT 1-2 HRS OVER THE NRN HIGH PLAINS. AN ACCOMPANYING
THREAT FOR LARGE HAIL AND DMGG WINDS WILL LIKELY REQUIRE WW ISSUANCE
BY 21Z.

DISCUSSION...19Z SFC ANALYSIS PLACES A COLD FRONT ACROSS FAR ERN
MT/WY...MOVING EWD INTO A PROGRESSIVELY MORE MOIST/UNSTABLE AIR MASS
ACROSS THE WRN DAKOTAS. VISIBLE SATELLITE IMAGERY INDICATES BUILDING
CU FIELD ALONG THE COLD FRONT...AS WELL AS OVER THE BLACK HILLS...AS
STRONG HEATING HAS ALLOWED TEMPERATURES TO REACH THE UPPER 70S/LOWER
80S. MEANWHILE...ASCENT ASSOCIATED WITH AN UPSTREAM UPPER TROUGH AND
ATTENDANT SPEED MAX NOSING INTO THE NRN PLAINS WILL ENHANCE THE
POTENTIAL FOR TSTM DEVELOPMENT THIS AFTERNOON.

SFC OBS INDICATE MOST NUMERICAL GUIDANCE /INCLUDING LATEST VERSIONS
OF THE RAP/ IS UNDERESTIMATING BOUNDARY LAYER MOISTURE...AND
SUBSEQUENTLY AMOUNT OF AVAILABLE CAPE. MODIFIED FORECAST SOUNDINGS
SUGGEST THAT SBCAPE VALUES OF AROUND 1500 J/KG ARE PRESENT. COMBINED
WITH FAVORABLE VEERING WIND PROFILES /YIELDING EFFECTIVE SHEAR
VALUES GREATER THAN 40 KTS/ AND INCREASING FORCED ASCENT
ACCOMPANYING THE AFOREMENTIONED UPPER TROUGH...THE POTENTIAL FOR
SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL AND DMGG WIND GUSTS...AND
PERHAPS AN ISOLATED TORNADO...WILL LIKELY REQUIRE ISSUANCE OF A WW.

..ROGERS/MEAD.. 06/13/2012

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

ATTN...WFO...ABR...BIS...UNR...

LAT...LON 47440103 45390070 43860089 43560205 43700342 43980393
45350390 46980399 47490341 47600229 47620157 47440103

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