The reason? Massive amounts of smoke has made its was southward from the wildfires in British Columbia and westward from the several fires in eastern Washington.
|Seattle at 6:23 AM Tuesday. Can you see the sun?|
The latest Washington State Air Quality Map shows unhealthy conditions over western Washington, with some locations (like Port Angeles, Cheeka Peek near Tatoosh, and several locations on the eastern slopes of the Cascades) reaching very unhealthy and hazardous conditions.
In fact, air quality is better in Beijing right now (see graphic)
Yesterday's noon image from the NASA MODIS satellite over the region was stunning. You can see the smoke moving into western WA from Canada and eastern WA and there was an amazing, long smoke front over southern Washington.
Here is Seattle (Puget Sound Clean Air Agency Duwamish site), the smoke (PM.5) surged yesterday afternoon, peaking this morning to around 80 mg per cubic meter (1-hr average).
This was by far the highest value this summer. To give you some context, here is the same plot since late May. Nothing close. There was a minor peak on July 4/5 of about 1/3 the value.
Solar radiation is being substantially reduced by the smoke. Here are plots on the UW Atmospheric Sciences roof for yesterday and August 9th (before the smoke). Down about 14%. The result will be substantially cooling of today's highs by at least 5 F based on recent experience with our WRF model.
The good news is that low level air quality should improve later today over Puget Sound and NW Washington, as suggested by the latest forecast of the NOAA/NWS HRRR smoke system. But smoke will return eventually.
And as I will talk about in a later blog, smoke forecasting has improved dramatically in recent years, giving meteorologists a powerful tool in warning folks of degrading air quality from wildfires.