BC Wildfire Smoke Heading for Washington State

Smoke update 9 AM Friday: Expect much lower concentrations of smoke aloft in Western Washington, peaking Saturday morning.

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As a record-breaking heat wave winds down, another summer weather hazard will show up in our backyard. Wildfire smoke from British Columbia fires is likely to arrive in Washington State by Saturday. 

The good news for Western Washington is that this smoke will be aloft, or high in the atmosphere...NOT impacting air quality. The same cannot be said for east of the Cascades, especially the northern tier of Eastern Washington.

First...where are these fires? The answer is north of the border, in British Columbia. Below is the BC Wildfire Dashboard as of 2 PM Thursday.

All orange icons are "new" fires, red dots are out-of-control fires, and flame icons represent "fires of note." Green and yellow dots are fires that are under control or being held, respectively. Notice the massive amount of new fire starts in the SE area of the Cariboo fire center. The BC Wildfire Service reports that 52% of new fires were started by lightning. 

One of the Service's "fires of note" is the Lytton Fire. On Tuesday (29th), Lytton, BC recorded Canada's hottest temperature ever, at a whopping 121F. In the 2 days since, 90% of the town has tragically been destroyed by a wildfire. The CBC News article below talks about this ongoing and tragic situation.

https://www.cbc.ca/news/canada/british-columbia/bc-wildfires-lytton-july-1-2021-1.6087311

The Lytton Fire is just one of the 82 active fires in BC that will send smoke into Washington. Let’s take a look at the HRRR-Smoke model’s forecasts for Washington. First, we’ll check out vertically integrated smoke, which is smoke in a vertical column of the atmosphere…not near the surface. 

Here’s 11 AM Friday.

Some smoke is present from fires in Oregon and California, but that is far from Western WA. Very light smoke concentrations are over our area. However, a large plume of smoke is moving south into Washington state.

The plume’s advance will be quite slow. By 9 PM Friday, around sunset, it will have made it south approximately to a line from Seattle to Spokane.

Other plumes of smoke are present aloft over NorCal, Oregon, Idaho, and Montana.

By 7 AM Saturday, the BC smoke plume has covered most of Washington state with smoke aloft. The concentration of smoke is relatively high, and I expect it will be quite noticeable in the sky, but not impacting Western WA air quality.

By 11 AM Saturday, the plume has moved eastward (very slightly), and is still over Western Washington.

This is the current limit of the forecast, so stay tuned as details evolve on the extent of this smoke situation. 

Now, let’s take a look at near-surface smoke at 11 AM Saturday. This smoke has an impact on air quality.

This is good news for Western Washington, which has virtually no near-surface smoke! However, expect degradation of air quality for most of Eastern Washington, especially in the northern half, where near-surface smoke concentrations are high because winds will blow smoke straight across the border.

Another way to see this is a cross-section. The coast is on the left, Puget Sound is the big valley in the middle, and Eastern WA is the flat area on the right.

The same thing is clear. Smoke will be far above the surface in Western Washington, but in high concentrations near the surface in the mountains and Eastern WA by Saturday morning. 

Again, do not expect bad air quality in Western Washington. The degraded air quality will be in Eastern Washington for now.

Stay tuned as more details about the smoke become clear.