Wildfire Smoke Impacts Expected across Washington through this Weekend

Local fires will be the primary source of surface smoke

Upper level smoke from fires in Idaho, Montana, and Canada will be transported toward Washington, as well

The Eagle Bluff Fire burning near the Canadian border in the Okanogan Valley has been consistently producing smoke since its ignition last weekend, but the Sourdough Fire burning above Diablo Lake has increased smoke production remarkably in the past 24 hours. Below you can see the location and current smoke plumes of those fires, as of Thursday, 3 August. Additionally, the Margarita Fire, located on the Pacific Coast near Moclips, produced smoke impacts for the south Puget Sound yesterday and may continue to smolder through Friday. Minor smoke impacts associated with that fire are likely to be contained near the coast.

The Sourdough Fire, in particular, will produce the most substantial smoke impacts over the next 24-48 hours in Washington. Winds will be out of the west during the day, blowing smoke toward the Okanogan Highlands and the Methow Valley, while at night, winds will reverse and blow smoke easterly into the Skagit River Valley toward Marblemount and Rockport. AQI values in the Orange/Unhealthy for Sensitive Groups range are possible at these locations, with further reduction in AQI possible near Diablo Lake. 

WSDOT is asking the public to not stop along SR-20 to take photos of the fire.

Sourdough Fire Update: Our maintenance crews took this photo of the wildfire burning near Diablo Dam in Whatcom County.
📋More info: https://t.co/3vJJPWXty6
⛔️Do not pull over to take photos or fly drones.
🚧Obey all road signs
➡️ Follow @NCascadesNPS https://t.co/TWNHLAxJiL pic.twitter.com/mQUyCf7649

— WSDOT North (@wsdot_north) August 3, 2023

Fortunately, cooler weather and precipitation chances are in the forecast for this weekend. The impact of smoke from the Eagle Bluff Fire has already been dramatically reduced by fire suppression efforts, and the upcoming weather will tamp down smoke production from the Sourdough Fire. Along with the precipitation, however, is a shift in the upper level winds that will draw elevated smoke from Idaho, Montana, and Canada toward Washington.  Below you can see the wind aloft over Washington expected for this weekend. 

The primary impact from the out-of-state smoke will be slight reductions in air quality across much of eastern Washington through the weekend, particularly overnight and through the morning hours. I do not anticipate widespread AQI in the Orange/Unhealthy for Sensitive Groups range, but Yellow/Moderate AQI will likely continue for areas such as Spokane, Colville, and the Tri-Cities. Widespread cloud cover this weekend across Washington will hide the dingy grey skies usually associated with wildfire smoke, so be sure to check the Washington Department of Ecology's Smoke & Fire page for the air quality in your area: Smoke & Fire Air Quality

Matthew Dehr

Wildfire Meteorologist