

144 

WWUS20 KWNS 112300

SEL6

SPC WW 112300

ILZ000-INZ000-MIZ000-LMZ000-120600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 286

NWS STORM PREDICTION CENTER NORMAN OK

555 PM CDT WED MAY 11 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST ILLINOIS

       NORTHERN INDIANA

       SOUTHWEST MICHIGAN

       LAKE MICHIGAN



EFFECTIVE THIS WEDNESDAY AFTERNOON AND THURSDAY MORNING FROM 555

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 NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTHEAST

OF KALAMAZOO MICHIGAN TO 30 MILES WEST SOUTHWEST OF MARSEILLES

ILLINOIS.  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 280...WW 281...WW

282...WW 283...WW 284...WW 285...



DISCUSSION...TSTMS EXPECTED TO CONTINUE DEVELOPING ALONG OUTFLOW

BOUNDARIES FROM EARLIER STORMS IN NRN IL.  OTHER STORMS EXPECTED TO

FORM IN THE NEXT FEW HRS OVER NRN IND AND SW MI...IN WAA ZONE N OF

WEAK WNW-ESE WARM FRONT.  AREA WILL BE GLANCED BY MODEST FORCING FOR

ASCENT ASSOCIATED WITH UPR IMPULSE MOVING NNE ACROSS ERN IA/WRN IL.

COUPLED WITH EXISTING DEGREE OF INSTABILITY...POTENTIAL WILL EXIST

FOR SVR HAIL AND LOCALLY DMGG WIND.  IF SUSTAINED DISCRETE STORMS

ARE ABLE TO ROOT INTO RECOVERING BOUNDARY LAYER OVER NRN IND/SW

MI...NOT A CERTAINTY ATTM...A THREAT FOR ISOLD TORNADOES MAY EVOLVE

GIVEN MODEST BUT RELATIVELY MOIST/BACKED LOW LVL FLOW N OF WARM

FRONT.



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 550. MEAN STORM

MOTION VECTOR 23025.





...CORFIDI

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