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WWUS20 KWNS 110131

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IAZ000-MNZ000-NEZ000-SDZ000-110900-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 643

NWS Storm Prediction Center Norman OK

835 PM CDT Tue Sep 10 2019



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Northwest Iowa

  Southwest Minnesota

  Northeast Nebraska

  Southeast South Dakota



* Effective this Tuesday night and Wednesday morning from 835 PM

  until 400 AM CDT.



* Primary threats include...

  Scattered damaging winds and isolated significant gusts to 75

    mph likely

  Scattered large hail and isolated very large hail events to 2

    inches in diameter possible

  A tornado or two possible



SUMMARY...Clusters of storms will continue to merge and grow upscale

into a larger convective system that will spread eastward overnight

with an attendant threat for damaging winds and large hail.  In the

short term, a supercell moving into Bon Homme County South Dakota

will pose a threat for a tornado or two before being overtaken and

merging with the clusters to the west.



The severe thunderstorm watch area is approximately along and 45

statute miles north and south of a line from 35 miles northwest of

Oneill NE to 20 miles north northeast of Spencer IA. For a complete

depiction of the watch see the associated watch outline update

(WOUS64 KWNS WOU3).



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...This severe thunderstorm watch replaces

severe thunderstorm watch number 642. Watch number 642 will not

be in effect after 835 PM CDT. CONTINUE...WW 640...WW 641...



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

2 inches. Extreme turbulence and surface wind gusts to 65 knots. A

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

27025.



...Thompson

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