SEVERE THUNDERSTORM WATCH FOR PORTIONS OF EASTERN MONTANA WESTERN NORTH DAKOTA NORTHWEST SOUTH DAKOTA NORTHEAST WYOMING EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 205 PM UNTIL 900 PM MDT

URGENT - IMMEDIATE BROADCAST REQUESTED   SEVERE THUNDERSTORM WATCH NUMBER 551   NWS STORM PREDICTION CENTER NORMAN OK   205 PM MDT THU AUG 2 2012      THE NWS STORM PREDICTION CENTER HAS ISSUED A   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF              EASTERN MONTANA          WESTERN NORTH DAKOTA          NORTHWEST SOUTH DAKOTA          NORTHEAST WYOMING      EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 205 PM UNTIL   900 PM MDT.      HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70   MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.      THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85   STATUTE MILES EAST AND WEST OF A LINE FROM 80 MILES EAST OF   GILLETTE WYOMING TO 50 MILES NORTHEAST OF WOLF POINT MONTANA.    FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH   OUTLINE UPDATE (WOUS64 KWNS WOU1).      REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE   FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY   DO PRODUCE TORNADOES.      OTHER WATCH INFORMATION...CONTINUE...WW 550...      DISCUSSION...STORMS ARE INTENSIFYING OVER SERN MT AND NERN WY ALONG   A DRY LINE/CONVERGENCE ZONE...WHILE NEW CU/TCU IS EVIDENT IN   SATELLITE IMAGERY FARTHER NORTH INTO NERN MT WHERE LOW LEVEL   MOISTURE WITH SURFACE DEW POINTS REMAIN IN THE 50S.  INITIAL ARC OF   WARM ADVECTION CONVECTION FROM NERN MT INTO SWRN ND IS EXPECTED TO   PROGRESS EWD WITH ADDITIONAL STRONG/SEVERE STORMS DEVELOPING OVER   ERN MT AND NERN WY.  STEEP LAPSE RATES ARE CONTRIBUTING TO MLCAPE OF   1000-1500 J/KG...AND 30-40 KT WESTERLY MID LEVEL WINDS ARE RESULTING   IN SUFFICIENT DEEP LAYER SHEAR TO SUPPORT ORGANIZED SEVERE STORMS   INTO THE EVENING HOURS AS ACTIVITY SPREADS EWD.      AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT   TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM   MOTION VECTOR 27025.