We all remember how smoky it was in 2017. The Pacific Northwest saw multiple periods of thick smoke through August 2017, and on September 5, ash fell over the city for first time since a trace fell when Mt. St. Helens erupted on May 18, 1980. I never thought in my wildest dreams that I’d see a smoke season in Seattle that would rival 2017, but 2018 has not only rivaled but surpassed last summer.
Interestingly, fire activity over the Pacific Northwest and British Columbia was remarkably quiet through July, and while we saw a little smoke from fires over Southern Oregon and California to finish off the month, the smoke was confined to the upper atmosphere and had little impact on air quality at the surface. However, we saw a dramatic pattern shift to begin in August, with a large ridge of high pressure developing over our region while a deep trough of low pressure sat offshore. This pumped warm, moist and unstable air into the Northwest, resulting in quite a bit of thunderstorm activity over British Columbia.
Photo courtesy Sara Robertson
These thunderstorms started numerous fires, and these fires grew dramatically during the second week of August as strong onshore flow temporarily returned to the area. As soon as winds calmed down again, the smoke from these now-raging fires simply built up over Southern British Columbia. And when northerly winds on the backside of an upper-level-low passing through our area during mid-August finally sent this reservoir of thick smoke southward into the Pacific Northwest, air quality quickly deteriorated to “Unhealthy” levels west of the Cascade crest and downright “Hazardous” levels over Eastern Washington. By Wednesday, August 15, the smoke over Western Washington was so thick that most locations around Puget Sound set daily records for the amount of particulate matter in the atmosphere, a record they would hold for less than a week.
Things got as bad as I’ve ever seen them in Seattle beginning Sunday, August 19th as another upper-level-low plunged southward from British Columbia and brought even more smoke into the area with it, both from the fires over British Columbia and some new fires over the North/Central Washington Cascades.
I remember waiting to catch the Greyhound bus to Portland Sunday evening and seeing visibility drop dramatically from 4–5pm as this smoke surged southward into the area. Though I was in Portland for the 20th and 21st where air quality was better, I heard stories of burning throats and eyes and saw pictures of ash on cars and a dim, blood-red sun obscured by all the smoke. Incredibly, Seattle’s air quality over these two days was five times worse than the average air quality over Beijing for July 2018.
Is the smoke we’ve seen over the past two years a sign of things to come in the future? I’m no expert on wildfires, but I do know that the past two years have had pretty good conditions for large, destructive wildfires, with wet springs creating above-average low-level foliage and dry, hot summers turning all this foliage into tinder-dry fuel for fires to feast on. There’s no doubt that poor forest management practices, such as planting trees in fire-prone areas such as Eastern Washington unnaturally close together, has made it easier for wildfires to grow, and the influx of people moving into the countryside has resulted in an increased number of fires.
Considering all of these other variables, it is tough to pin down the effect that global warming has on wildfires: it may cause wildfire seasons to begin slightly earlier as temperatures warm and fuels dry more quickly, and more extended warmth could allow for drier fuels. However, this says nothing about the amount of foliage available to burn or the direction of the winds that carry smoke into certain regions. 2014 and 2015 actually had far more wildfire activity over Washington than 2017 or 2018, but the smoke we’ve seen over these past two years has made this fire season seem much worse.
If all the smoke has got you down, just remember that we only have two months until November! By then, wildfires will be the least of our worries.
Charlie is a Leschi native and now works in Portland as a meteorologist for Portland General Electric. Be sure to check out his weather blog at www.charlie.weathertogether.net.