Washington Smoke Blog

Friday, July 30, 2021

Western WA outlook: Some smoke upstairs, but good on the ground floor…

Western Washington has mostly lucked out so far this year when it comes to wildfire smoke. We can thank a steady flow of clean air from the Pacific Ocean, except for a short visit from that in-law we’re all trying to forget, a certain heat-dome that probably deserves its own name. But I’ll save that for another time.

Anyway, 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. The HRRR model shows a decent plume arriving in western Washington late Friday afternoon, with another wave heading in overnight and into Saturday. Here’s some more details:

So far, the Pacific Northwest has mostly been getting clean marine air flowing west to east . But a ripple in the pressure patterns has sent smoke from Northern California and Oregon to the northwest, and right for us. This is forecast to arrive late Friday afternoon. (See the first figure, which shows the sum of smoke at all levels, like looking down from a satellite) The pressure gradient in central and eastern Washington, and further east, will also shift on Friday and Saturday and start sending smoke to us, too. Saturday late afternoon, we’ll get another wave of smoke from central and eastern Washington and British Columbia.

But what does this mean for Western Washington air quality? … 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.

While two waves of smoke are expected to reach our skies, they’ll be at 2 km or higher (see the second figure), and the situation at 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. Although the upstairs smoke and the downstairs marine air generally keep to themselves, there’s a chance that a few of the upstairs visitors might trickle downstairs and push us to MODERATE air quality.

To add to this mix, the warmer temperatures are bringing us elevated ozone (smog) conditions. The atmosphere cooks up ozone from the emissions of cars, trucks, industry, and even plants. In the summer, when the temperatures get turned up to the 80s and 90s, the ozone can build up to levels that are considered Unhealthy for Sensitive Groups. Because the “cooking” of the urban emissions takes time and the winds during these hot episodes are to the east, the high ozone levels mostly occur in the foothills of the Cascades and not in the urban core. Today (Friday) we’re likely to see highs around 90, which means ozone might reach Unhealthy for Sensitive Groups. Saturday will still be hot, but will have some clouds, so the “cooking” won’t be as fast, so we should stay in the Moderate air quality category, for ozone, and therefore overall… assuming no smoke sneaks down from upstairs.

If the forecast holds, the Puget Sound should continue to have GOOD to MODERATE air quality downstairs, even though the upstairs will look hazy. And, hopefully, we won’t get much lightning in the Cascades.

Thursday, July 29, 2021

Eastern WA smoke and weekend outlook (watch for a Western WA outlook tomorrow)

Spare a thought for our neighbors in Okanogan County who are facing what appears to be the earliest start to smoke season. The plot below shows how fine particle pollution levels have evolved between June and September each year since permanent monitors were established in the county. This year (thick red line) spiked earlier than other years, but thankfully not as high as some previous years which we all prefer to forget.

This morning's satellite picture shows how south winds from yesterday have continued to push the smoke northward. However this upper level wind pattern can only do so much with high pressure building in to the area.

No doubt the British Columbians love us dearly for all that.

Good news is that a decent amount of rain is expected in the North Cascades Sunday into Monday, aiding firefighting efforts. But first we've got to get through a scorching weekend with little wind. An Air Quality Alert is in effect for the northern counties.

Elsewhere in eastern WA

We expect some smoke from Oregon fires to start moving over the Columbia Basin from Friday, causing Moderate air which could later degrade to Unhealthy for Sensitive Groups. Here's a snapshot of all the different forecasts (aka "ensemble models") we have for Spokane and Colville, for the next 5 days. Although there's a wide spread among predictions, Unhealthy air cannot be ruled out.

Please use the resources on this blog to safeguard your health during smoke events.

Check out the technicalese explanation of our ensemble smoke forecast system here.

Tuesday, July 27, 2021

7/27/2021 Smoke Blog Update

We've implemented a minor redesign to the blog and added a new tab for our readers to quickly and easily access the custom smoke forecasts prepared by Air Resource Advisors assigned to incident management teams working in Washington. Notice the new tab along the top border of the blog content area and click on "LOCAL SMOKE OUTLOOKS" to access the forecasts.

Interested in smoke forecasts prepared for other states? You can find the full set of smoke outlooks prepared by Air Resource Advisors at this link: https://wildlandfiresmoke.net/outlooks