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WWUS20 KWNS 111348

SEL2

SPC WW 111348

ILZ000-INZ000-LMZ000-111800-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 422

NWS Storm Prediction Center Norman OK

850 AM CDT Wed Aug 11 2021



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Northern Illinois

  Extreme northwestern Indiana

  Lake Michigan



* Effective this Wednesday morning and afternoon from 850 AM

  until 100 PM CDT.



* Primary threats include...

  Scattered damaging winds and isolated significant gusts to 75

    mph likely

  Scattered large hail and isolated very large hail events to 2

    inches in diameter possible

  A tornado or two possible



SUMMARY...An intensifying storm cluster in northwest Illinois has

shown signs of increasing organization this morning.  The downstream

environment favors maintenance of the storms, and the potential for

swaths of damaging winds with isolated significant gusts to 75 mph,

occasional large hail, and possibly a tornado or two with embedded

circulations.



The severe thunderstorm watch area is approximately along and 35

statute miles north and south of a line from 25 miles west northwest

of Marseilles IL to 5 miles east of Valparaiso IN. For a complete

depiction of the watch see the associated watch outline update

(WOUS64 KWNS WOU2).



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.



&&



AVIATION...A few severe thunderstorms with hail surface and aloft to

2 inches. Extreme turbulence and surface wind gusts to 65 knots. A

few cumulonimbi with maximum tops to 550. Mean storm motion vector

27045.



...Thompson

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