August 3, 2017  Current Air Quality Conditions Statewide and Tomorrow's Forecast.

A complex and dynamic air quality situation resides over the state.  Currently, Oregon is experiencing some of the worst air quality it has seen since August 2015, as shown below for noon Pacific Time.   The Willamette Valley is experiencing unhealthy air quality (red dots), while the northern portion of the state from the Columbia River Gorge to La Grande are experiencing unhealthy air for sensitive groups( orange dots).  Much of the remainder of the state is experiencing moderate conditions (yellow dots), except for Shady Cove where the air quality is a little worse (orange dot). 

So what’s causing this?   A combination of three factors are to blame (1) smoke coming down from the fires in British Columbia, (2) smoke from large fires within Oregon and surrounding states, and (3) ozone caused by the hot weather.   

Here’s a screen shot from Canada's Wildfire Smoke Prediction System (FireWork) showing the smoke originating from the fires in British Columbia for noon today, which has moved south into Washington, Idaho, and Oregon.  The color-coding indicates the density of the smoke with the highest concentrations in dark red and the lightest smoke in gray.  Much of Oregon is covered by this smoke with the heaviest concentrations located near Portland (and worse in Seattle).   

We are also getting smoke from the large wildfire fires in Oregon and surrounding states, as shown in the Blue Sky model output for today.  Notice the east winds bring smoke from the fires in the Cascades into western Oregon, and smoke from the fires in Idaho bring smoke into NE Oregon.

The National Weather Service's model shows where peak 1-hour ozone concentrations are forecasted to be the highest in the Pacific NW for today, as illustrated below.  Relatively high concentrations are shown over Portland and south through the Willamette Valley and further north along the I-5 corridor through Seattle.  Slightly higher ozone concentrations are also predicted around Medford and Boise.

So how long will this situation last?   The Willamette Valley will have one more day of unhealthy air quality with ozone and PM2.5 levels remaining high.  The air quality will improve dramatically by tomorrow night as the ridge of high pressure starts to breakdown and westerly winds resume.  That should clear out the smoke from the Canadian Fires.  However, this is bad news for Central and Eastern Oregon which will receive the Canadian smoke along with the smoke from the fires in the Cascades.  The image below shows the Canadian smoke model prediction for tomorrow at 9 pm Pacific Time.  

The smoke arising from the large wildfires over the Oregon Cascades will begin blowing towards the east by later this evening and continue through tomorrow (at least).  This will create addition smoke in central Oregon and southern Oregon tomorrow.  Klamath Falls is likely to receive the highest concentrations of smoke from these fires, although north of there, the Canadian fires should cause just as bad if not worse air quality conditions.

So what about those high ozone levels in Portland and Medford?  Expect one more day of that, as high temperatures and stagnant air remain present until the Westerly winds resume Friday night.