Sunday, August 6, 2017

Smoke might spare western WA by remaining above, not so further east

Mostly Good (Green) or Moderate (Yellow) air in western WA on Saturday in spite of plenty of smoke over the area as shown by the satellite image of Saturday afternoon.

This is because a temperature inversion is limiting downward mixing. Here's the 5PM temperature sounding from Quillayute on Saturday, showing the inversion:

Models persist with this 3000- 5000 ft inversion through Tuesday, and if that prediction holds, it should keep most of the smoke above. Other models however mix some smoke to surface during the daytime hours on Sunday and Monday, so uncertainty persists. Air could range from Good to Unhealthy for Sensitive Groups in western WA, with both smoke and smog contributing- more on smog later.

Eastern WA doesnt have such a temperature inversion to keep the smoke aloft, so as long as the northerly flow persists, BC smoke will continue to mix downward. Air quality is not expected to improve a whole lot all week. Although a few Moderate areas might appear occasionally, folks need to be prepared for a repeat of the above map. Air will remain Unhealthy for Sensitive Groups, if not worse.

A pattern shift that will help us ventilate out isn't on the cards until Saturday. The 10K ft winds advertised by the European model only turn southwest for the first time in over a week on Saturday morning.

And now about smog: the importance of ground level ozone (O3- the key ingredient of smog; not to be confused with "good" stratospheric ozone) has gotten lost in the midst of all the fine particle pollution concerns. Ozone is not released directly from sources but is formed when certain gases react together in the atmosphere under hot, dry and sunny conditions. It irritates the eyes, nose, throat, and respiratory system and is especially bad for those with chronic heart and lung disease, children and the elderly. A brief summary can be found here.

Wildfires are copious sources of one of the precursor gases and many ozone monitors in WA recorded high levels of ozone over the last few days.

Even when wildfire smoke is taken out of the equation, Washington state continues to have ozone concerns in the Cascade foothills of east King/ Pierce county, and in the Tri-Cities. Several air quality agencies are working with stakeholders to protect the public from this health risk.

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