Sunday, August 11, 2019

Drenching, gusty storms to accompany cooler air in northwestern US through Sunday

By Renee Duff, AccuWeather meteorologist




Additional heavy and severe thunderstorms will erupt across the northwestern United States as cooler air moves in through the weekend.
The thunderstorms may not only bring lightning dangers and torrential downpours, but also threaten localized damage in some communities.
Heavy rain triggered a mudslide on State Route 410 in the Washington Cascades on Friday night. Washington Department of Transportation crews cleared the roadway and opened it back up to motorists on Saturday afternoon. 

On Saturday night, Washington State Route 821 in the Yakima River Canyon was closed in both directions from north of Selah to near Ellensburg due to a rock slide over the roadway. An estimated time to open the roadway has not yet been determined.
A dip in the jet stream associated with a chilly pocket of air high in the atmosphere is causing the stormy pattern. 

"This time of the year, when the air aloft is chilly, the August sun still heats the ground and creates a volatile atmosphere that can trigger an eruption of thunderstorms," AccuWeather Senior Meteorologist Alex Sosnowski said. 
NW Sun Aug 10

While much of Oregon dries out at the end of the weekend, rain and thunderstorms will continue to spread northeastward on Sunday, drenching eastern Washington through Montana.
Some of the thunderstorms in Montana could be severe, packing damaging winds, large hail and torrential downpours.
Hikers are urged to monitor the sky for darkening clouds. If thunder is heard while you are in the high terrain and no vehicle or building is nearby, head to a valley or depression in the landscape away from lone trees.
While the wet weather may disrupt travel and outdoor plans for some, the rainfall will be welcome where abnormally dry to moderate drought conditions exist.
Most of the meaningful rainfall will miss the severe drought areas of western Washington.
The drought has been a breeding ground for wildfires, with around two dozen large fires currently burning in the Northwest, according to InciWeb.
The pattern through this weekend will help to douse some of these blazes. However, any lightning in the absence of meaningful rainfall can create sparks that ignite new blazes.
The cloudier, wetter weather will keep temperatures from reaching the record heights from earlier this past week.
In Spokane, Washington, the high came close to 100 degrees Fahrenheit at midweek, but is forecast to stay in the 60s on Sunday. Boise will drop from a seasonable high of 93 on Friday to the upper 70s on Sunday. 
Early week Aug 10

"Through the first half of the week, the jet stream is forecast to take on a relatively straight west-to-east configuration," Sosnowski said.
This will allow warmer, drier weather to return to the Northwest as early as Monday and Tuesday.
However, rain may make a return appearance as the jet stream dips down again later in the week.
Download the free AccuWeather app to keep track of severe thunderstorms and temperature trends in your area. Keep checking back for updates on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
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