MESOSCALE DISCUSSION 1152

        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               ATTN...WFO...ABR...BIS...UNR...          LAT...LON   47440103 45390070 43860089 43560205 43700342 43980393                 45350390 46980399 47490341 47600229 47620157 47440103