Weekend Smoke Forecast: A Change In The Air For Puget Sound

SEATTLE — While much of the country has contended with wildfire smoke for weeks, Western Washington remained shielded, thanks to a consistent pattern of clean air from the Pacific Ocean flowing west to east. Now, Puget Sound is in for a slight change of fortune as the latest air quality forecasts predict two waves of smoke trickling in through the weekend.

"That steady flow of clean air can't hold up all summer, and indeed it seems to be changing on Friday, Saturday, and into Sunday," wrote Philip Swartzendruber, an air quality scientist with the Puget Sound Clean Air Agency. "The HRRR model shows a decent plume arriving in western Washington late Friday afternoon, with another wave heading in overnight and into Saturday."

On the Washington Smoke Blog, Swartzendruber wrote that the unwelcome visit is thanks to "a ripple in the pressure patterns" that is sending smoke from wildfires burning in Northern California and Oregon straight to Western Washington.

The good news, forecasters said, is that models suggest impacts to air quality on the ground should be minimal, and it appears unlikely conditions will dip into the more hazardous ranges.

"It looks to be a classic upstairs-downstairs situation, in which most of us in the lowlands of Puget Sound and Western Washington will likely be spared, while smoke passes overhead," Swartzendruber wrote. "While two waves of smoke are expected to reach our skies, they'll be at 2 km or higher...and the situation at the surface should be very different. Over the weekend, there will still be a pressure gradient at the surface from the coast to the western side of the Cascades. So, clean marine should continue to push in, to at least the foothills."

While there is a chance some of that "upstairs" smoke could filter down Saturday and Sunday, the latest forecasts suggest air quality should remain in the "moderate" range or better, despite the haze. Air quality may be worse at higher elevations and near the Cascades. According to the Puget Sound Clean Air Agency, westerly winds should return by late Sunday and push out the remaining smoke.

Smoke and air quality resources:

• Washington Smoke Blog
• Daily air quality forecasts
• Wildfire smoke preparedness tips
• AirNow's live smoke and air quality maps

Apart from the smoke, Saturday is forecast to be partly sunny, with afternoon temperatures in the high 80s to low 90s. Sunday looks to be a few degrees cooler and cloudier. The forecast for the first few days of August has temperatures near normal, with mostly sunny skies and temperatures in the low 80s.