A Smoke Storm is About to Hit Washington State

Western Washington has escaped serious wildfire smoke at the surface, but that is about to change tonight and tomorrow.

A serious smoke storm will invade western and eastern Washington, and those that are vulnerable should prepare.

The smoke layer was evident from Crystal Mountain this morning

The visible satellite imagery this morning shows smoke over eastern Washington and a band of smoke extending over western Washington (see below)

Over the west side, this smoke is currently aloft, while serious smoke is surfacing over eastern Washington.  Reflecting this situation, air quality shown in the AIRNOW plot (below) is generally good (green dots) west of the Cascade crest (except in the Fraser River Valley).  But eastern Washington and BC have many locations with poor and even unhealthy (red and purple) conditions.  

Ironically, the smoke aloft is greatly reducing solar radiation reaching the surface and will take the edge off the heat today.  Still quite hot, but it would have been several degrees warmer without the smoke aloft.  For example, it is COOLER today at SeaTac than yesterday.....that is the smoke effect.

But things are about change in a major way and a large amount of smoke is about to invade western Washington.  The air quality will decline greatly.

There are still a substantial number of large wildfires in southern British Columbia and their smoke has been kept away by the general eastward winds from off the Pacific.

But that is going to change tonight as northerly and northeasterly flow strengthens over the region, pushing dense smoke toward Washington State...and particularly western Washington.   

To illustrate what will happen, let me show you the near-surface smoke predicted by the NOAA HRRR model.

The situation at 7AM this morning indicates clean air over western WA and NW Oregon, but smoky air from BC and eastern WA fires evident to the east (red colors).

But by 5 PM today serious smoke has surfaced in portions of western Oregon and Washington, and dense smoke (purple colors) is moving our way.

And by 5 AM tomorrow (Friday) serious smoke will be over the Cascades and into Northwest Washington, from Tacoma northward.  Bellingham looks particularly bad.

At 5 PM tomorrow unhealthy surface air will extend from Portland to Vancouver--better along the coast. You will probably smell it.

Fortunately, the smoke storm in western WA should end on Saturday, as cleaner air moves in off the ocean.  But still bad for our friends in eastern Washington.

I have given a lot of study to airflow and smoke in our region.  The "secret" of getting smoke to the surface in densely populated western Washington is to have fires in BC and northeasterly flow aloft.   Air moving down the western slopes of the Cascades allows higher-level smoke to be pushed to near sea level.

Dealing With the Smoke

If you are vulnerable/sensitive to smoke, there are several things you can do.

If you have N95 filters because of the COVID situation, use them.  They are also highly effective in removing wildfire smoke particles. Cloth masks will be of marginal benefit.

If you are lucky enough to have an air conditioning system with a decent air filter, use it.  Good filters are MERV 13 or FPR 10  or better.

If you have central heating with a good air filter, turn the fan on and close the windows.

You can create an excellent air filter system by attaching a box fan to a good air filter (see image).  My colleagues at the Puget Sound Clean Air Agency have created an excellent video on how to do this.

Of course, there are a number of excellent commercial portable air filtration systems you can purchase.

Finally, several municipalities, such as Seattle, have designed public buildings with good air filtration.

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Announcements:  

I will be doing a special online session with my Patreon supporters on Saturday at 10 AM.

Several of you have asked whether I will be doing a blog on the latest UN IPCC Climate Assessment.  The answer is yes.  In fact, the blog is written, but I wanted to give priority to the heatwave and smoke situation.