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WWUS20 KWNS 282204

SEL7

SPC WW 282204

IAZ000-ILZ000-MOZ000-290400-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 357

NWS Storm Prediction Center Norman OK

505 PM CDT Tue Aug 28 2018



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Southeastern Iowa

  Northwestern Illinois

  Northeastern Missouri



* Effective this Tuesday afternoon and evening from 505 PM until

  1100 PM CDT.



* Primary threats include...

  Scattered large hail likely with isolated very large hail events

    to 2 inches in diameter possible

  Scattered damaging wind gusts to 70 mph likely

  A tornado or two possible



SUMMARY...A band of storms has quickly formed and intensified from

northern Missouri into southern Iowa, and these storms will likely

expand into a larger cluster while spreading eastward through late

evening.  Embedded supercells with large hail/damaging winds are

expected initially, and a transition to a more linear mode with

damaging winds is expected through late evening.  There will be some

potential for a tornado or two, especially across southeastern Iowa,

as storms interact with a diffuse outflow boundary.



The severe thunderstorm watch area is approximately along and 65

statute miles north and south of a line from 55 miles south

southwest of Knoxville IA to 30 miles east southeast of Moline IL.

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 356...



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 550. Mean storm motion vector

26030.



...Thompson

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