SEL6 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 296 NWS STORM PREDICTION CENTER NORMAN OK 335 PM CDT THU MAY 24 2012 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF CENTRAL AND EASTERN IOWA EXTREME NORTHWEST ILLINOIS SOUTHWEST WISCONSIN EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 335 PM UNTIL 1000 PM CDT. HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES WEST NORTHWEST OF LONEROCK WISCONSIN TO 35 MILES SOUTH SOUTHWEST OF OTTUMWA IOWA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6). 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 295... DISCUSSION...STORMS ARE DEVELOPING ALONG AN EWD MOVING COLD FRONT OVER THE CENTRAL PARTS OF IA AND ACTIVITY IS EXPECTED TO INTENSIFY THROUGH THE LATE AFTERNOON HOURS. CONVECTION WILL BE MOVING INTO AN ENVIRONMENT CHARACTERIZED BY SBCAPE OF 1500-2000 J/KG AND VERY STRONG LOW AND MID LEVEL SHEAR. LOW LEVEL INVERTED-V SOUNDINGS WILL AID IN DEVELOPMENT OF STRONG DOWNDRAFTS...ESPECIALLY OVER ERN IA WHERE DCAPE EXCEEDS 1000 J/KG. DAMAGING WIND GUSTS AND OCCASIONAL HAIL WILL BE THE PRIMARY SEVERE THREATS. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 22040. ...WEISS
SEL5 URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 295 NWS STORM PREDICTION CENTER NORMAN OK 225 PM CDT THU MAY 24 2012 THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF WESTERN AND CENTRAL UPPER MICHIGAN SOUTHEAST MINNESOTA NORTHERN AND WESTERN WISCONSIN LAKE SUPERIOR EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 225 PM UNTIL 1000 PM CDT. TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTH SOUTHWEST OF LA CROSSE WISCONSIN TO 40 MILES NORTHEAST OF IRONWOOD MICHIGAN. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5). 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. DISCUSSION...THUNDERSTORMS ARE BEGINNING TO INCREASE IN COVERAGE ALONG A COLD FRONT FROM SRN MN INTO NRN IA IN RESPONSE TO INCREASING FORCING AHEAD OF A STRONG SHORT WAVE TROUGH APPROACHING FROM THE SOUTHWEST. STORMS ARE LIKELY TO INTENSIFY INTO NWRN/WEST CENTRAL WI THIS AFTERNOON AS A DEEPENING SURFACE LOW MOVES NNEWD ALONG A PRE-EXISTING THERMAL GRADIENT...WITH ACTIVITY PROGRESSING EWD/NEWD THROUGH THE EVENING. ALTHOUGH LOW LEVEL MOISTURE IS SOMEWHAT MARGINAL...STRONG FORCING AND INTENSE VERTICAL SHEAR WILL PROMOTE DEVELOPMENT OF BOWING LINE SEGMENTS AND OCCASIONAL EMBEDDED SUPERCELLS WITH ATTENDANT THREATS FOR WIND DAMAGE AND A FEW TORNADOES. AVIATION...TORNADOES AND 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 22045. ...WEISS
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