Seems like we got through the 4th of July fireworks with no major, widespread degradation in air quality. North Bend and Marysville briefly recorded Unhealthy air last evening and several other sites are reporting Moderate air this morning. There is evidence that light amounts of Alaskan wildfire smoke did mix down to the surface today, as advertised by the Canadian smoke model. More on that below for anyone interested.
Expect Moderate air in splotches today as residual smoke clears out slowly during the day, and thereafter it should be mostly Good air statewide this weekend. There is nothing in the forecast over the next 5 days to suggest a major warm up or drying out. Temperatures around normal and slightly higher than normal precip all work against wildfires. We'll keep our focus on smoke transported from more distant sources.
About that Alaskan wildfire smoke theory
On Wednesday, the Canadian smoke model (also called "Firework", incidentally) was the only one which predicted Alaskan smoke will mix to the surface this morning. It was the most pessimistic of the suite of smoke models we use, but proved correct. How do we know that? Consider the following:
- Timing of some of the increases in fine particle pollution levels: firework- induced (i.e. the loud, smoky and flashy ones, not complex software running on servers north of 49 degrees latitude) pollution typically spikes on the evening and night of July 4th and declines thereafter. Several sites in eastern WA show concentrations flatlining at Moderate levels into this morning without much of a decline. Sunnyside, Chelan and the Methow Valley in particular.
- Monitors in southern British Columbia, where fireworks aren't a factor on 7/4, also showed gradual increases this AM. While it is possible that some WA firework pollution may have been transported there (travel time of a few hours), the concentrations haven't declined like they did at our firework- smoke affected sites. Also, not all sites close to border crossings show evidence of a plume passing by late at night.
- Satellite pictures this morning show a thin layer of smoke aloft and the above points suggest it did mix to the surface, albeit in small quantities.