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756 

WWUS20 KWNS 301909

SEL4

SPC WW 301909

ILZ000-INZ000-MIZ000-WIZ000-LHZ000-LMZ000-310200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 504

NWS STORM PREDICTION CENTER NORMAN OK

210 PM CDT FRI AUG 30 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHERN ILLINOIS

  NORTHERN INDIANA

  SOUTHERN LOWER MICHIGAN

  SOUTHERN WISCONSIN

  LAKE HURON

  LAKE MICHIGAN



* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 210 PM UNTIL

  900 PM CDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 2

    INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST OF

ROCKFORD ILLINOIS TO 35 MILES EAST NORTHEAST OF FLINT MICHIGAN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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.



&&



DISCUSSION...GRADUAL THUNDERSTORM DEVELOPMENT IS ONGOING NEAR A

SLOWLY SOUTHEASTWARD-MOVING COLD FRONT...WHERE A MOIST BOUNDARY

LAYER CONTINUES TO HEAT/DESTABILIZE.  AS INSTABILITY MAXIMIZES OVER

THE NEXT COUPLE OF HOURS...STORMS ARE EXPECTED TO CONTINUE

INCREASING IN COVERAGE AND INTENSITY -- AIDED BY MODERATE

NORTHWESTERLY FLOW ALOFT.  THE STRONGEST CELLS WILL BE CAPABLE OF

PRODUCING LARGE HAIL AND LOCALLY DAMAGING WINDS AS THEY SHIFT

SOUTHEASTWARD INTO THE EVENING HOURS.



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 500. MEAN STORM

MOTION VECTOR 28030.





...GOSS

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