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WWUS20 KWNS 042031

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URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 478

NWS Storm Prediction Center Norman OK

430 PM EDT Mon Sep 4 2017



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Central and northeastern Indiana

  Southeastern Lower Michigan

  Northwestern Ohio

  Lake Erie

  Lake Huron



* Effective this Monday afternoon and evening from 430 PM until

  1100 PM EDT.



* Primary threats include...

  Widespread damaging wind gusts to 70 mph likely

  Isolated large hail events to 1.5 inches in diameter possible



SUMMARY...Thunderstorm development is expected in the next 1-2 hours

along a cold front moving southeastward across Lower Michigan and

northern Indiana.  The storms should evolve rather quickly into a

line, and the storm environment will favor damaging winds with most

storms in the squall line through late evening.



The severe thunderstorm watch area is approximately along and 55

statute miles north and south of a line from 20 miles north

northwest of Terre Haute IN to 35 miles southeast of Mount Clemens

MI. For a complete depiction of the watch see the associated watch

outline update (WOUS64 KWNS WOU8).



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

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

few cumulonimbi with maximum tops to 500. Mean storm motion vector

29040.



...Thompson

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