Seattle’s above-normal temperatures have been tempered somewhat by a grimy layer of smoke from British Columbia’s wildfires that moved in Tuesday. The influx has made air quality in and around the Emerald City worse than Beijing’s.
Even as the air cools a bit over the weekend, the temperatures will stay far above normal, with the haze dissipating only somewhat and quite slowly, says KNKX weather expert Cliff Mass, a professor of Atmospheric Sciences at the University of Washington.
“Last night, the winds started switching to onshore, westerly flow. And that’s going to have an effect over a period of time,” Mass said on Friday.
“So I think we’ve seen the worst air quality and I think over the next few days the air’s going to start to clear. But it’s going to stay warm.”
The smoke comes at a time of sustained temperatures that have been way above normal and likely peaked on Thursday when they were originally projected to go several degrees higher than they actually did. The smoke kept them down by about 3-5 degrees on Wednesday and by as much as 5-10 degrees in some locations, Mass said.
Scorching Heat, Even Tempered By Smoke
Still, Mass called Thursday’s temps “amazing” as Seattle hit 94 and Portland soared as high as 105.
“What I found really startling was some places, downstream of the Olympics – on the southern side of the Olympics – temperatures got over 100 degrees,” Mass said.
At Quillayute, for example, a coastal measuring station west of Forks, the mercury hit 99 degrees on Wednesday, tying its all-time record high temperature.
Portland had been projected to reach an all-time record high of 108 or 109 degrees, but “only got to 105 degrees,” Mass said. And Seattle reached 94, rather than about 100. But 94 is still way above normal, Mass said.
“It was just an amazingly warm period. And I’m afraid although it’s going to cool down a bit, we’re still going to be well above normal for several days," he said.
Weekend Forecast: A Bit Cooler
Friday, he says to expect temperatures around 90. On Saturday it will be a smidgen cooler: in the upper 80s. Then it should get back to about 90 on Sunday, followed by a very slow and gradual cool-off after that.
“This time of the year, temperatures should be around 76,” Mass said. “So, we’re averaging on the order of 15 degrees or more above normal. And that’s going to continue – not quite as warm -- at least into the middle of next week.”
Seattle Headed For Dry-day Record
Mass says there is no rain at all in the forecast, which makes it increasingly likely that the region will tie or break records for consecutive dry days. And there's nothing immediate to wash away the particulate matter that's come with the smoke.
“I think the big record – 51 days of no measurable rain – is one that we are going to break this week,” Mass said.
That’s based mainly on data gathered at Sea-Tac Airport, which had reached 47 days without measurable precipitation as of the end of Thursday.
‘Smokezilla’ Came From British Columbia
Mass has been calling the smoky weather pattern we’re experiencing ‘Smokezilla’ on his blog, where he gives a blow-by-blow description of how pressure dynamics in the atmosphere pushed the smoke in on Tuesday. He also explains the scenario that's causing it to stick around.
He says of course he’s having a bit of fun with the comic-inspired nickname, but that the air quality issues shouldn’t be taken lightly.
“This is a fairly severe smoke period for us. Two years ago we had another smoky time. But this one is a little bit stronger and a little bit more sustained – of any smoke period I’ve seen around here in western Washington.”
In fact, he says measurements he checked on Wednesday showed Seattle’s air quality far worse than that of Beijing, based on measurements of particulate matter.
“The concentrations there were one-sixth to one-eighth of the concentrations we had here,” Mass said.
“So the air was actually much cleaner in Beijing than in Seattle. And that’s not very normal.”
To hear the full conversation, you can click on the 'play' icon at the top of this post.
Weather with Cliff Mass airs at 9:02 a.m. Friday, right after BirdNote, and twice on Friday afternoons during All Things Considered. The feature is hosted by KNKX environment reporter Bellamy Pailthorp. Cliff Mass is a University of Washington professor of atmospheric sciences, a renowned Seattle weather prognosticator, and a popular weather blogger. You can also subscribe to podcasts of Weather with Cliff Mass shows, via iTunes or Google Play.