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WWUS20 KWNS 211352

SEL9

SPC WW 211352

SDZ000-211900-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 459

NWS Storm Prediction Center Norman OK

855 AM CDT Mon Aug 21 2017



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Southern South Dakota



* Effective this Monday morning and afternoon from 855 AM until

  200 PM CDT.



* Primary threats include...

  Isolated very large hail events to 2 inches in diameter possible

  Isolated damaging wind gusts to 70 mph possible



SUMMARY...A pair of intense storms should move east-southeast across

south-central SD through midday with a risk of severe hail and wind.



The severe thunderstorm watch area is approximately along and 50

statute miles north and south of a line from 90 miles west of

Chamberlain SD to 25 miles south of Mitchell SD. For a complete

depiction of the watch see the associated watch outline update

(WOUS64 KWNS WOU9).



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 60 knots. A

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

29030.



...Grams

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