Much of the West has been plagued by heat and smoke but a change in the weather pattern will lead to cooler conditions and better air quality by as early as tomorrow (Thursday). A trough will build into the West through the end of this week into the weekend (see Fig. 1). This will allow cooler air to advect into the region. The greatest impacts will be felt across the Pacific Northwest (PNW) but impacts will not be limited to the Pacific Northwest–the Southwest will cool down as well.
Fig. 1: Trough building into the PNW
Temperatures will fall a good 15 to 30 degrees across parts of the PNW with more subtle cooling across parts of the Southwest but still allowing for below normal temperatures (see Fig. 2). For the PNW, high temperatures will be in the 60s to low 70s in the low elevations with higher elevations remaining in the 40s. There is even the possibility of snow for the highest elevations in the Cascades and northern Rockies where a few inches may fall. If you have plans to go up to Mount Rainer, snow will be likely from late week through the weekend. An increase in precipitation is likely for the region, too.
Fig. 2: Climate Prediction Center temperature probabilities (days 6-10)
Along withe the cooler temperatures and increase in precipitation chances, the air quality will improve as the trough builds in (see Fig. 3 and 4). It should be noted, this pattern change will change the direction of the surface winds, which will impact fire movement for wildfires that are not contained.
Fig. 3: Near-surface smoke (this morning)
Fig. 4: Near-surface smoke (Friday)