Summer returns this week, but what about smoke?

At the time of writing, the state is almost entirely cloud free. What you dont see clearly in this short satellite animation is a very thin layer of Alaskan smoke that is drifting over western WA, likely contributing a little fine particle pollution to our ground level monitors. Some Puget Sound area monitors briefly showed Moderate air this morning.

Western WA forecast

The Canadian model shows this smoke mostly blowing offshore and staying away after today. Winds wont become dead calm today or tomorrow, so chances of lingering smoke are low. Barring new fires in the area, fine particle pollution levels are expected to remain Good, with perhaps a few splotches of Moderate through Wednesday. Ozone however, is another story. See below.

Eastern WA forecast
No major fires at present, neither is the area expected to be downwind of any fires through Wednesday. However there's a long list of small fires at any given time, and conditions are right for their growth this week. Expecting mostly Good air through Wednesday except near fires. The public is strongly encouraged to do their due diligence and exercise utmost caution to prevent the spread of fires.

Ozone
Conditions are right for ozone (smog) formation Tuesday & Wednesday on both sides of the Cascades. Problem spots are around Enumclaw and Yelm in western WA, and Kennewick in the east. Some periods of Moderate air should be expected. Ozonematters.com provides succinct information on proactive steps that can be taken to minimize ozone pollution.

However it must be mentioned that summer 2019 hasn't had many high ozone days. Here's a plot showing how Kennewick's ozone days and potential ozone days compared with past years. Potential ozone days (gray bars) are when the day's weather lined up with historical meteorological conditions under which elevated ozone levels were observed. It is clear that there were fewer days where weather was conducive for ozone this summer, even when the rest of the summer is taken in account.

Our next blog post will provide a smoke forecast for Labor Day weekend, and we will also explore some of the reasons why this summer has been a low smoke year thus far.