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WWUS20 KWNS 212316

SEL7

SPC WW 212316

ILZ000-INZ000-LMZ000-220500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 407

NWS STORM PREDICTION CENTER NORMAN OK

615 PM CDT THU JUL 21 2016



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHERN ILLINOIS

  EXTREME NORTHWEST INDIANA

  LAKE MICHIGAN



* EFFECTIVE THIS THURSDAY NIGHT FROM 615 PM UNTIL MIDNIGHT CDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED DAMAGING WIND GUSTS TO 70 MPH LIKELY

  ISOLATED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE



SUMMARY...A BOWING THUNDERSTORM CLUSTER IN SOUTHEAST WISCONSIN WILL

LIKELY CONTINUE TO SURGE TO THE SOUTHEAST INTO THE CHICAGO AREA

THROUGH LATE EVENING...WITH THE RISK FOR DAMAGING WINDS AND SOME

LARGE HAIL.  ADDITIONAL THUNDERSTORM DEVELOPMENT IS ALSO EXPECTED ON

THE WEST FLANK OF THE ONGOING CLUSTER INTO SOUTH CENTRAL AND

SOUTHWEST WISCONSIN.  THESE STORMS WILL SUBSEQUENTLY MOVE INTO NORTH

CENTRAL/NORTHWEST ILLINOIS WITH AN ATTENDANT DAMAGING WIND/HAIL RISK

INTO THE EARLY OVERNIGHT HOURS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTHEAST OF

ROCKFORD ILLINOIS TO 50 MILES SOUTH SOUTHEAST OF MARSEILLES

ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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 406...



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM

MOTION VECTOR 34035.





...THOMPSON

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