SEL0 URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 360 NWS STORM PREDICTION CENTER NORMAN OK 235 PM MDT TUE JUN 5 2012 THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF NORTH-CENTRAL AND CENTRAL MONTANA EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 235 PM UNTIL 1100 PM MDT. TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES SOUTH SOUTHEAST OF GREAT FALLS MONTANA TO 65 MILES EAST NORTHEAST OF CUT BANK MONTANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0). REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. OTHER WATCH INFORMATION...CONTINUE...WW 358...WW 359... DISCUSSION...MIGRATORY SURFACE LOW NEAR LVM WILL DEVELOP NWD ALONG N-S ORIENTED WARM FRONT TO VICINITY OF HVR BY LATE EVENING. AIR MASS ALONG THIS BOUNDARY IS QUITE MOIST GIVEN THE ELEVATION WITH DEWPOINTS IN THE MID 50S-LOWER 60S. WHEN COUPLED WITH STEEP MIDLEVEL LAPSE RATES...ENVIRONMENT IS MODERATELY UNSTABLE WITH MLCAPE OF 1000-2000 J/KG AND A DECREASING CAP. EXPECT TSTMS TO INCREASE IN COVERAGE AND INTENSITY THIS AFTERNOON INTO EVENING IN RESPONSE TO APPROACH OF NEGATIVELY TILTED MIDLEVEL TROUGH. FORECAST HODOGRAPHS ALONG THE WARM FRONT DEPICT SIZABLE LOW- AND DEEP-LAYER SHEAR WHICH WILL SUPPORT SUPERCELLS CAPABLE OF A FEW TORNADOES...IN ADDITION TO VERY LARGE HAIL AND DAMAGING WINDS. AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 17035.
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