'Super-Massive' Smoke Plume Bears Down On Western Washington

SEATTLE, WA — A combined smoke plume from wildfires burning in California and Oregon has migrated northward and is expected to hamper air quality in Western Washington until at least Sunday, forecasters said.

The Washington Smoke Blog, a partnership between state, county, federal and tribal agencies, began tracking a "super-massive body of smoke" as it filtered into Southwest Washington Thursday. According to the smoke alert, that plume is expected to impact Western Washington, the Columbia Basin and Spokane as it pours across the breadth of the state.

Incredible images shared widely Wednesday showed smoke enveloping California's Bay Area and several towns around Oregon. More than 3.1 million acres have burned across the Golden State this year, including the state's largest wildfire on record: the 471,000-acre August Complex. In Oregon, 500,000 people are under evacuation right now, amounting to 10 percent of the state's population.

Latest: Washington Air Quality Forecast: How Long Will The Smoke Last?

Smoke from California and Oregon began to move into Washington Thursday morning, slowly progressing north through the evening and moving across the I-5 corridor early Friday morning, quickly tanking air quality. By mid-morning, Seattle, Bellevue, Bremerton, Olympia and Tacoma had readings in the "very unhealthy" range, with "hazardous" air recorded in Shelton and Aberdeen. Within a couple hours, the Seattle region joined the hazardous category.

Local wildfires have impeded air quality for several days, largely due to smoke from fires burning in Central and Eastern Washington. The National Weather Service has extended a region-wide air quality alert into Monday morning, citing the new smoke arriving from the south.

According to forecasters, the earliest chance at a reprieve now appears to be Sunday, when more marine air should push into the interior and gradually improve air quality from west to east. The first chance for rain is Monday. In Seattle, Mayor Jenny Durkan said all city parks, boat ramps, athletic fields, golf courses and beaches would be closed through at least the weekend.

Ranil Dhammapala, an atmospheric scientist with the Department of Ecology, wrote Thursday afternoon that predicting precisely when and where the smoke will hit hardest can prove difficult.

Dhammapala said the department has been overwhelmed with requests for personalized forecasts and will share new details as much as possible. To plan for the wider impact of smoke, residents can view an online air quality forecast map that is updated daily.

"This is to be used as a general guideline only, not for dissecting with surgical precision the differences in air quality on one street and the next," Dhammapala wrote.

Saturday is likely to be worse than Friday in some areas, and Dhammapala said clean air well be "a relative term" for most of the weekend.

Current air quality conditions can be found on the Puget Sound Clean Air Agency and Department of Ecology websites. Both agencies' Twitter feeds also feature regular updates. More information on the smoke outlook will be posted on the Washington Smoke Blog.