SEL7 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 397 NWS STORM PREDICTION CENTER NORMAN OK 515 PM CDT FRI JUN 15 2012 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF NORTHERN NEBRASKA CENTRAL SOUTH DAKOTA EFFECTIVE THIS FRIDAY AFTERNOON AND SATURDAY MORNING FROM 515 PM UNTIL 100 AM CDT. 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 55 STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH NORTHWEST OF MOBRIDGE SOUTH DAKOTA TO 60 MILES SOUTH SOUTHWEST OF VALENTINE NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7). 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 395...WW 396... DISCUSSION...STORMS DEVELOPING WITHIN LEE-SIDE/THERMAL LOW AND DEVELOPING WARN FRONT ACROSS SD SHOULD CONTINUE TO SPREAD EAST ALONG THE NEB/SD BORDER AND ALSO INTO AREAS OF CENTRAL SD THROUGH THE EVENING HOURS. REGION LIES WITHIN/BENEATH MID LEVEL JET STREAK THAT IS PROVIDING DEEP SHEAR SUPPORTIVE OF STORM ORGANIZATION AND PERSISTENCE. IN ADDITION TO LARGE HAIL WITH INITIAL CELLULAR DEVELOPMENT...STORM MERGERS AND SOME UPSCALE GROWTH WITHIN THE DEEP-LAYER WLY FLOW REGIME...AND INCREASE IN NOCTURNAL LLJ...COULD CONTRIBUTE TO MCS DEVELOPMENT WITH AN INCREASING CHANCE FOR MORE NUMEROUS SEVERE OR NEAR SEVERE WIND EVENTS WITH TIME. 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 450. MEAN STORM MOTION VECTOR 27015.
No comments:
Post a Comment