MESOSCALE DISCUSSION 1053

        MESOSCALE DISCUSSION 1053     NWS STORM PREDICTION CENTER NORMAN OK     0317 PM CDT MON JUN 04 2012          AREAS AFFECTED...PORTIONS OF NRN/CNTRL/WRN MT          CONCERNING...SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY           VALID 042017Z - 042145Z          PROBABILITY OF WATCH ISSUANCE...95 PERCENT          SUMMARY...THE THREAT FOR SEVERE THUNDERSTORMS WILL INCREASE THIS     AFTERNOON ACROSS PARTS OF MONTANA. LARGE HAIL AND DAMAGING WINDS     WILL BE THE PRIMARY CONCERNS WITH THIS ACTIVITY...AND A SVR TSTM     WATCH WILL BE ISSUED BY 2100Z. WHILE A TORNADO THREAT CANNOT BE     RULED OUT ACROSS PARTS OF CNTRL/N-CNTRL MT.          DISCUSSION...EARLY-AFTERNOON SFC MESOANALYSIS PLACES A WARM FRONT     EXTENDING FROM A LOW OVER NERN ORE EWD ACROSS CNTRL ID INTO SWRN MT     THAT ARCS NEWD INTO E-CNTRL MT BEFORE EXTENDING SEWD INTO THE     DAKOTAS. A NE-SW ORIENTED ZONE OF SFC PRESSURE FALLS AOA 2 MB PER 2     HRS EXTENDS FROM NEAR THE HAVRE AREA SWWD TOWARD GREAT FALLS AND     FARTHER SW INTO SWRN MT AND E-CNTRL ID....WHICH LIKELY REFLECTS THE     COMBINED IMPACTS OF MODEST LEE CYCLOGENESIS SUPERIMPOSED ON     INCREASING LARGE-SCALE FORCING FOR ASCENT. THE ISALLOBARIC RESPONSE     TO THE PRESSURE FALLS WILL HELP THE FRONT GRADUALLY ADVANCE NWD     THROUGH LATE AFTERNOON WHILE STRONG INSOLATION/DIABATIC HEATING     CONTINUES TO ERODE ANTECEDENT CONVECTIVE INHIBITION.          A PLUME OF RELATIVELY RICH LOW-LEVEL MOISTURE...WITH SFC DEWPOINTS     IN THE UPPER 40S TO THE 50S...EXTENDS ACROSS ERN MT...AND INTO PARTS     OF CNTRL MT NORTH OF THE WARM FRONT. THESE DEWPOINTS SHOULD BE     MAINTAINED THROUGH THE AFTERNOON WHILE TEMPERATURES CONTINUE TO     RISE...AS VERTICAL MIXING OCCURS INTO ENHANCED PACIFIC MOISTURE     OVERLAYING THE AREA /PW VALUES IN EXCESS OF 0.8 INCH PER GPS DATA/.     GIVEN THE AFOREMENTIONED LOW-LEVEL MOISTURE BENEATH 700-500-MB LAPSE     RATES OF 7-8 C/KM...MLCAPE VALUES WILL LIKELY INCREASE TO 750-1500     J/KG. TOWERING CUMULUS FIELD IS BECOMING INCREASINGLY AGITATED PER     VISIBLE SATELLITE IMAGERY FROM SWRN MT INTO CNTRL ID...WHERE CINH IS     FIRST TO BE ERODED AS MOUNTAINS SERVE AS ELEVATED HEAT SOURCES.     STORMS WILL TRACK QUICKLY NNEWD TO ENEWD ACROSS THE NRN ROCKY     MOUNTAIN FRONT AND ADJACENT HIGH PLAINS OF CNTRL/N-CNTRL MT INTO THE     EARLY EVENING.          GIVEN STRONG MID-LEVEL FLOW SUPPORTING 45-55 KT OF DEEP     SHEAR...JUXTAPOSED WITH THE AFOREMENTIONED BUOYANCY...PERSISTENT     SUPERCELL STRUCTURES WILL BE POSSIBLE /POSSIBLY EVOLVING INTO BOWING     LINE SEGMENTS/...ESPECIALLY WITH CONVECTION ACROSS CNTRL/N-CNTRL MT     NEAR AND NORTH OF THE WARM FRONT. SVR WIND/HAIL WILL BE OF CONCERN     WITH THESE STORMS...AND SOME SIGNIFICANTLY SVR WIND WILL BE POSSIBLE     AS DCAPE VALUES CLIMB TO 1000-1300 J/KG.          A TORNADO THREAT MAY ALSO DEVELOP WITH THE STRONGEST/MOST PERSISTENT     SUPERCELLS NEAR AND NORTH OF THE FRONT...EAST OF THE FRONT RANGE     TOWARD GREAT FALLS AND HAVRE. BACKED SFC WINDS IN THESE AREAS WILL     SUPPORT THE GREATEST LOW-LEVEL HODOGRAPH CURVATURE.     HOWEVER...RELATIVELY HIGH LFC/LCL HEIGHTS AND AT LEAST MODEST SFC     TEMPERATURE-DEWPOINT SPREADS...WILL ALSO ACT TO LIMIT THE TORNADO     POTENTIAL. THIS AREA WILL CONTINUE TO BE MONITORED FOR A POTENTIAL     UPGRADE TO A TORNADO WATCH LATER THIS AFTERNOON INTO THE     EVENING...SHOULD A SUPERCELL THREAT APPEAR MORE LIKELY TO EVOLVE     WITHIN THE HELICITY-RICH ENVIRONMENT NEAR AND NORTH OF THE WARM     FRONT.          ..COHEN/CARBIN.. 06/04/2012               ATTN...WFO...BYZ...GGW...TFX...