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WWUS20 KWNS 132058

SEL1

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COZ000-KSZ000-NEZ000-SDZ000-140500-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 451

NWS Storm Prediction Center Norman OK

400 PM CDT Sun Aug 13 2017



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Eastern Colorado

  Northwest Kansas

  West-central and northern Nebraska

  Southeast South Dakota



* Effective this Sunday afternoon from 400 PM until Midnight CDT.



* Primary threats include...

  Scattered large hail and isolated very large hail events to 3

    inches in diameter possible

  Isolated damaging wind gusts to 70 mph possible

  A tornado or two possible



SUMMARY...Severe thunderstorms will continue to develop through late

afternoon in vicinity of a surface boundary and spread

east/southeastward through the late afternoon and evening hours.

Ample instability and shear will support supercells capable of very

large hail, particularly across west-central Nebraska into western

Kansas. Damaging winds will also be a concern and a tornado cannot

be entirely ruled out.



The severe thunderstorm watch area is approximately along and 70

statute miles east and west of a line from 50 miles north northwest

of Yankton SD to 45 miles south southeast of Burlington CO. For a

complete depiction of the watch see the associated watch outline

update (WOUS64 KWNS WOU1).



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 450...



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

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

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

30025.



...Guyer

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