

063 

WWUS20 KWNS 172107

SEL9

SPC WW 172107

COZ000-NEZ000-SDZ000-WYZ000-180500-



URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 279

NWS Storm Prediction Center Norman OK

310 PM MDT Tue Jul 17 2018



The NWS Storm Prediction Center has issued a



* Severe Thunderstorm Watch for portions of

  Northeast Colorado

  Western Nebraska

  Southwest South Dakota

  Eastern Wyoming



* Effective this Tuesday afternoon and evening from 310 PM until

  1100 PM MDT.



* Primary threats include...

  Scattered large hail and isolated very large hail events to 2

    inches in diameter possible

  Scattered damaging wind gusts to 70 mph possible

  A tornado or two possible



SUMMARY...Relatively isolated strong to severe thunderstorms at

mid-afternoon should gradually increase in coverage and intensity

through late afternoon and early evening within an increasingly

unstable air mass across the High Plains. A relatively moist air

mass and strengthening winds aloft will support some supercells

capable of large hail. Storms may eventually cluster into a

semi-organized system capable of localized wind damage later this

evening.



The severe thunderstorm watch area is approximately along and 80

statute miles east and west of a line from 40 miles northeast of

Gillette WY to 25 miles south of Akron CO. 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.



&&



OTHER WATCH INFORMATION...CONTINUE...WW 278...



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 500. Mean storm motion vector

28025.



...Guyer

