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MTZ000-NEZ000-SDZ000-WYZ000-070200-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 409

NWS Storm Prediction Center Norman OK

140 PM MDT Fri Aug 6 2021



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Extreme southeastern Montana

  The northwestern Nebraska Panhandle

  Western South Dakota

  Central and northeastern Wyoming



* Effective this Friday afternoon and evening from 140 PM until

  800 PM MDT.



* Primary threats include...

  Scattered damaging wind gusts to 70 mph possible

  Isolated large hail events to 1 inch in diameter possible



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

intensity this afternoon from central into northeastern Wyoming, and

storms will spread into the northwestern Nebraska Panhandle and

western South Dakota later this afternoon into this evening.  The

storm environment favors organized, high-based storm clusters with a

primary threat of damaging outflow winds to near 70 mph.  Isolated

supercells may also occur in central Wyoming, where isolated large

hail to near 1 inch diameter will be possible.



The severe thunderstorm watch area is approximately along and 125

statute miles east and west of a line from 85 miles northeast of

Gillette WY to 35 miles southwest of Douglas WY. 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

1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few

cumulonimbi with maximum tops to 500. Mean storm motion vector

25035.



...Thompson

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