SEL1 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 391 NWS STORM PREDICTION CENTER NORMAN OK 330 PM CDT THU JUN 14 2012 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF WESTERN AND NORTH-CENTRAL IOWA EASTERN NEBRASKA EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 330 PM UNTIL 1100 PM CDT. HAIL TO 2.5 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 60 STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHEAST OF SPENCER IOWA TO 15 MILES SOUTH OF LINCOLN NEBRASKA. 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 389...WW 390... DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY THIS AFTERNOON ALONG AND AHEAD OF COLD FRONT WHERE AIR MASS HAS BECOME MODERATE-STRONGLY UNSTABLE WITH MLCAPE OF 2000-4000+ J/KG. VERTICAL SHEAR WILL REMAIN RELATIVELY WEAK...BUT THE CHARACTER OF THE THERMODYNAMIC ENVIRONMENT WILL FOSTER INTENSE UP/DOWNDRAFTS CAPABLE OF DAMAGING WINDS AND LARGE HAIL. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 27020. ...MEAD
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