Severe T'Storm Watch

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
EASTERN IOWA...NORTHERN ILLINOIS...SOUTHERN AND EASTERN WISCONSIN...LAKE MICHIGAN EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 450 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 70 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES NORTH NORTHWEST OF CEDAR RAPIDS IOWA TO 35 MILES EAST OF OSHKOSH WISCONSIN. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
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.

DISCUSSION...THUNDERSTORMS WILL INITIATE AND INCREASE IN COVERAGE ALONG AND AHEAD OF A SEWD MOVING COLD FRONT. THE AIRMASS AHEAD OF THE FRONT IS STRONGLY UNSTABLE WITH 40 TO 50 KT OF DEEP LAYER SHEAR WHICH WILL RESULT IN A SEVERE THREAT DEVELOPING ACROSS THE WATCH AREA FROM LATE THIS AFTERNOON INTO THE MID-EVENING. ALTHOUGH A TORNADO OR TWO WILL BE POSSIBLE AS LOW-LEVEL FLOW INCREASES THIS EVENING...THE MAIN THREATS ARE EXPECTED TO BE LARGE HAIL AND WIND DAMAGE AS STORMS CONGEAL AND DEVELOP INTO A LINE-SEGMENT.