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Statewide Smoke Forecast for Tuesday and Wednesday

The Air Quality Index at noon on Tuesday, Aug. 14, 2018.  See the map above for current conditions.

Forecast Issued:  Aug. 14, 2018
Forecaster:  James Miller, USDA Forest Service
At noon on Tuesday, Aug. 14, 2018, major air quality impacts were occurring across the majority of Oregon, a dramatic change from Monday morning when many locations were reporting good air quality. Smoke from wildfires burning in British Columbia and Washington drifted into Northern Oregon during the early evening hours on Monday, lowering air quality to the moderate category for much of the Portland metro area, with moderate to unhealthy for sensitive groups air quality in the northeastern part of the state.
Overnight, more smoke aloft settled into lower elevations causing the air quality to deteriorate to unhealthy for sensitive groups or unhealthy levels across all of Northern Oregon, including the Portland metro area. As a result, the Oregon Department of Environmental Quality  issued an air quality advisory for Portland, Northeastern Oregon, and portions of the Willamette Valley. In addition, DEQ extended the air quality advisory already in place for Jackson and Josephine counties and portions of Klamath County through the weekend.
For the rest of Tuesday, air quality is not expected to improve significantly anywhere in the state. In fact, air quality will likely deteriorate for areas not yet impacted by wildfire smoke. This includes Cottage Grove, the Eugene metro area, and Roseburg, where air quality was in the good category at noon on Tuesday. However, by the late afternoon and early evening hours, additional wildfire smoke will enter the southern Willamette Valley, likely lowering air quality to unhealthy for sensitive groups.
On Wednesday, most Oregon locations will continue to experience degraded air quality and hazy skies, though some improvement in air quality may occur in the Portland metro area due to a switch to westerly (onshore) winds during the daytime. Regardless, skies throughout the western portion of the state will remain hazy due to upper-level smoke moving north from Southwest Oregon, which is expected to continue for the next several days. The High-Resolution Rapid Refresh Model model forecasts that the biggest improvement in air quality and visibility on Wednesday will likely occur along the Oregon coast coinciding with the shift to westerly (onshore) winds.
In summary, the state of Oregon is currently experiencing major air quality impacts with these expected to continue for the next 24 to 36 hours until the thermal trough currently west of the Cascades moves east of the mountains bringing marine air into Northwestern Oregon. However, this will not reduce smoke high above the surface, thus skies will remain hazy even if surface air quality improves throughout the Willamette Valley. Southwestern Oregon will likely experience the most persistent smoke impacts and generally worst air quality in the state continuing into the weekend.

Above: Near-surface smoke forecast from the High-Resolution Rapid Refresh (HRRR) Model for Tuesday,
Aug. 14, 2018 at 6 p.m. (left) and Wednesday, August 15, 2018 at 4 p.m. (right).