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Statewide Smoke Forecast for Tuesday through Thursday Aug. 21-23, 2018

The Air Quality Index at 9 a.m. on Tuesday, Aug. 21, 2018.  See the map above for current conditions.

Forecast Issued:  Aug. 21, 2018
Forecaster:  James Miller, USDA Forest Service

As of 10 a.m. on Tuesday, Aug. 21, 2018, all air quality monitors in the Oregon were reporting air quality indices in the moderate or worse category. Unhealthy conditions prevailed from Portland to Salem while further south in the Willamette Valley, unhealthy for sensitive groups air quality was observed in the Eugene metro area. Compared to yesterday morning, conditions have improved in Northeastern Oregon where generally moderate to unhealthy for sensitive groups air quality was reported during the late morning hours on Tuesday. In Central and Southern Oregon, including Ashland, Bend, Klamath Falls, Lakeview and Medford, unhealthy air quality indices were observed Tuesday morning.

For the remainder of Tuesday, there are no major changes to the forecast made yesterday. Throughout the state, air quality will remain degraded on Tuesday from fires burning to our north in British Columbia and Washington, and from those in Southern Oregon. The latest High-Resolution Rapid Refresh Model indicates there should be some air quality improvement on Tuesday afternoon for Northeastern Oregon and possibly Northern Oregon west of the Cascades, though much of this depends on fire behavior to the north in Washington. However, it does appear that smoke levels have decreased somewhat in parts of Northern Oregon as seen in the late morning web cam images from the U.S. Forest Service’s Columbia Gorge (CORI1) and Mount Hood (MOHO2) IMPROVE air quality monitoring locations. While still very hazy at both locations, conditions are better than 24 hours ago (see yesterday’s statewide forecast for a comparison). Unfortunately, conditions in Central and Southern Oregon are not expected to improve Tuesday.

View west from the Columbia Gorge IMPROVE air quality monitor near Wishram, WA at 10:45 a.m. on Tuesday, August 21, 2018. See current image.

View south from the Mount Hood IMPROVE air quality monitor near Government Camp, OR at 10:45 a.m. on Tuesday, Aug. 21, 2018. See current image.

Late on Tuesday and into Wednesday, air quality should begin to improve for the northern half of the state, especially east of the Cascades. However, west of the Cascades in the Willamette Valley, the High-Resolution Rapid Refresh Model suggests that smoke currently over Western Washington will move into Northwestern Oregon, affecting coastal communities as well as the central and northern Willamette Valley. This smoke over Northwestern Oregon should begin to push eastward by midday on Wednesday, but air quality impacts will likely remain until late into the day on Wednesday for Northwestern Oregon. Much improved conditions are expected over the majority of Northern Oregon on Thursday when a strong marine push brings westerly winds that should effectively scour out the remaining smoke over the northern zones.

For Central and Southern Oregon, there may be some air quality improvement on Wednesday, but currently the forecast still indicates that smoky conditions will prevail over the central and southern coastal zones, the Southern Willamette Valley (e.g. Eugene), and the major cities of Southern Oregon. As has been the case for several weeks now, Ashland, Klamath Falls, Lakeview, and Medford will experience heavy smoke levels leading to air quality indices likely in the unhealthy for sensitive groups or worse category throughout the day Wednesday, with localized unhealthy to hazardous conditions possible near wildfires burning in the region.

Overall, residents and visitors to the state of Oregon should expect major air quality impacts to continue throughout Tuesday, with some potential improvement on Wednesday, especially in the north. By Thursday, conditions are expected to improve considerably for a large portion of the state as a major weather pattern shift occurs that should lower temperatures to slightly below seasonal averages under westerly to northwesterly flow.

Near-surface smoke forecast from the High-Resolution Rapid Refresh (HRRR) Model for Tuesday, Aug. 21, 2018 at 4 p.m. (top) and Wednesday, Aug. 22, 2018 at 4 p.m. (bottom).

Disclaimer: Forecasting weather, fire behavior, and smoke transport and dispersion is challenging. While we strive to bring you the most up-to-date and accurate forecasts, conditions can and do change rapidly. Please take the appropriate action to protect yourself.