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WWUS20 KWNS 172236

SEL1

SPC WW 172236

NDZ000-SDZ000-WYZ000-180500-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 521

NWS Storm Prediction Center Norman OK

440 PM MDT Wed Jul 17 2019



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Extreme southwestern North Dakota

  Western South Dakota

  Extreme northeastern Wyoming



* Effective this Wednesday afternoon and evening from 440 PM

  until 1100 PM MDT.



* Primary threats include...

  Scattered large hail and isolated very large hail events to 2.5

    inches in diameter possible

  Scattered damaging wind gusts to 70 mph possible

  A tornado or two possible



SUMMARY...Thunderstorms are expected to increase in coverage this

evening from Wyoming into western South Dakota, and other more

isolated storms will likely persist across southwestern North

Dakota.  The storm environment favors supercells capable of

producing large hail as the primary threat, though an isolated

tornado cannot be ruled out near the Black Hills.  Some clustering

of storms will also be possible by late evening across western South

Dakota, with an attendant threat for damaging winds.



The severe thunderstorm watch area is approximately along and 75

statute miles east and west of a line from 45 miles northeast of

Lemmon SD to 55 miles south of Rapid City SD. 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 516...WW 517...WW

518...WW 519...WW 520...



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

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

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

28030.



...Thompson

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