

653 

WWUS20 KWNS 140351

SEL0

SPC WW 140351

ILZ000-INZ000-MIZ000-LMZ000-140900-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 300

NWS STORM PREDICTION CENTER NORMAN OK

1050 PM CDT WED MAY 13 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST ILLINOIS

       NORTHWEST INDIANA

       SOUTHWEST LOWER MICHIGAN

       LAKE MICHIGAN



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 1050 PM

UNTIL 400 AM CDT.



HAIL TO 1 INCH 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 35 MILES NORTH

NORTHEAST OF GRAND RAPIDS MICHIGAN TO 25 MILES SOUTH SOUTHWEST OF

DECATUR ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

TORNADO WATCH NUMBER 297. WATCH NUMBER 297 WILL NOT BE IN EFFECT

AFTER 1050 PM CDT. CONTINUE...WW 295...WW 296...WW 298...WW 299...



DISCUSSION...A BROKEN BAND OF STORMS WILL PIVOT EWD IN ADVANCE OF

THE COLD FRONT AND A STRONG MID LEVEL TROUGH MOVING EWD FROM IA/MN.

LOW-MID LEVEL FLOW WILL INCREASE AS THE MID LEVEL WAVE APPROACHES

LAKE MI OVERNIGHT.  DESPITE SOMEWHAT STABLE TEMPERATURE PROFILES

NEAR THE GROUND...MODEST LOW-LEVEL MOISTENING AND THE STRENGTHENING

FLOW WILL MAINTAIN A THREAT FOR DAMAGING WINDS WITH EMBEDDED

CELLS/BOWS THOUGHT THE EARLY MORNING HOURS.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.

A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM MOTION

VECTOR 25040.





...THOMPSON

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