Statewide Smoke Forecast through Thanksgiving Weekend

Forecast Issued: Nov. 16, 2018 
Forecaster: James Miller, USDA Forest Service

Overall, air quality across Oregon has either improved slightly or remained unchanged compared to yesterday morning. Locations in the Portland to Eugene corridor have experienced slight improvement, but still remain in the moderate air quality category. The most improvement has been within the Portland metro area, where several locations experienced unhealthy for sensitive groups air quality yesterday morning whereas good to moderate conditions were in place this morning. 

Figure 1. The Air Quality Index at 8 a.m. on Friday, November 16, 2018.  

For the rest of today, favorable low-level winds and upper-level atmospheric conditions from a passing weak-weather disturbance should lead to continued air quality improvement in the Willamette Valley, with good to moderate air quality expected in more locations by tomorrow.

Improved atmospheric mixing will also likely produce slight air quality improvement for most of the state by tomorrow, but high-pressure generally remains in place over the region through early next week, so air quality improvements may be short-lived, especially in Central and Southern Oregon. As a result, the Oregon Department of Environmental Quality extended an air stagnation advisory for Southern Oregon through Tuesday in addition to issuing a new advisory for Central Oregon that will be in place from Sunday through Wednesday.

Mid to upper level winds may also introduce smoke from California wildfires into southern portions of the state early next week. The return to weak low-level winds in central and Southern Oregon following a brief improvement in atmospheric mixing this afternoon through tomorrow will trap wood stove and wildfire smoke within valley locations.

However, at this time, we do not expect California wildfire smoke to impact Northern Oregon early next week, so air quality in the good to no worse than the moderate category is anticipated through midweek in the Willamette Valley.

Widespread good air quality should prevail by Thanksgiving into the post-holiday weekend as a more progressive weather pattern develops, bringing a chance of rain and mountain snow for most of the state.

Figure 2. Near-surface smoke forecast from the AIRPACT-5 model for Friday, Nov. 16, 2018 at 6 p.m.

Figure 3. Near-surface smoke forecast from the AIRPACT-5 model for Saturday, Nov. 17, 2018 at noon.

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