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WWUS20 KWNS 172238

SEL5

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IAZ000-ILZ000-MOZ000-LMZ000-180600-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 345

NWS Storm Prediction Center Norman OK

540 PM CDT Sat Jun 17 2017



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Southern and eastern Iowa

  Northern and central Illinois

  Northeast Missouri

  Lake Michigan



* Effective this Saturday afternoon and Sunday morning from 540

  PM until 100 AM CDT.



* Primary threats include...

  Scattered large hail and isolated very large hail events to 2.5

    inches in diameter possible

  Scattered damaging wind gusts to 70 mph possible

  A tornado or two possible



SUMMARY...Storms will continue to intensify generally near a front

where the preceding air mass is most and very unstable. With the aid

of an approaching mid/upper-level system and jet streak, relatively

strong deep-layer winds will help organize storms into

east/southeastward-moving bands through the evening. Damaging winds

and severe hail are the primary concerns.



The severe thunderstorm watch area is approximately along and 60

statute miles north and south of a line from 65 miles west northwest

of Quincy IL to 45 miles east of Marseilles IL. For a complete

depiction of the watch see the associated watch outline update

(WOUS64 KWNS WOU5).



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

2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A

few cumulonimbi with maximum tops to 600. Mean storm motion vector

28035.



...Guyer

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