August 26, 2018

Rain, Better Air Quality, And the End of Major Heat Waves for Perhaps the Rest of the Summer

With the upper level trough passage today, increasing onshore flow and rain has greatly cleaned up the air over the entire region.  In fact, as shown in the figure, the air quality over the Northwest hasn't been this good in months (green is the best).

And that is not all.  Many locations in western Washington did not get above the mid-60s, resulting in the coldest daytime highs since mid-June...something illustrated at Sea Tac AP:
The latest long-range ensemble forecasts (running the models many times) suggests no heat wave (over 80F) for the next two weeks  (the US/Canada NAEFS ensemble is shown below, temperatures are in °C, with 20C about 68F).   And by mid-September the sun is weakening rapidly, so the chances of major heat declines.
Although we undoubtedly will get a taste of more Canadian smoke this week, concentrations will probably be modest. 


  1. Great to take a full breath while I watched the sun rise here in Dungeness this morning.


  2. Is it possible to make a generalization about what amount of rainfall is required to suppress fires? (A tenth of an inch, a quarter inch, half inch, inch? And would it need to fall within, say, 24 hours?) And, what would be a typical date by which such rainfall could be expected in the current burn areas creating all this smoke: (a) Vancouver Island (b) interior British Columbia (c) Along and east of the Cascades and eastern Washington (d) Oregon?

    1. Wildfires are typically not completely suppressed until snow accumulates on the ground.


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