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Oregon State Smoke Forecast for Monday -Tuesday Sept. 4-5, 2017

Issued:  Sept. 3, 2017
Forecaster: R. Graw, USDA Forest Service

As of Sunday morning, there were 14 large uncontained, large fires in Oregon and eight new fires. Several of these large fires consists of multiple fires referred to as complexes.   Most of these fires extend north to south in the Cascade Mountains from the Washington to California border, as shown in Figure 1 below.

Figure 1.  Fires in Oregon as of Sunday morning, Sept. 3, 2017


 Monday, Sept. 4, 2017

A ridge of high pressure will remain over the state on Monday, as hot temperatures continue over the holiday weekend. This will cause a subsidence inversion and poor mixing of the atmosphere all day, keeping smoke trapped in the lower layers of the atmosphere.

Overnight tonight, nighttime drainage flows will bring smoke into their usual spots. By mid morning, smoke will begin to disperse as shown in Figure 2. For the western portion of the state, winds will be out of the north all day. This will bring  good air quality over the central and northern coast and Willamette Valley, but heavy smoke will continue to be present over Southwest Oregon, and the Central and Southern Cascades. An east wind will help keep Central and Eastern Oregon free of smoke all day. The Columbia River Gorge will experience some overnight drainage flows down Eagle Creek overnight, but then the north wind will bring some smoke into the Gorge all the way to Pendleton and as far south as Bend by evening.

Figure 2.  Model-Predicted 24-hour Average Smoke Concentrations for Monday Sept. 4, 2017

Tuesday Sept. 5, 2017

Easterly winds in the Cascades and the Gorge will start to increase as high pressure builds east of the Cascades and the thermal trough builds up into the Willamette Valley. This will transport  much of the smoke from the Cascades into the western portion of the state out to the coast, as shown in Figure 3. The new Eagle Creek fire in the Columbia River Gorge along with smoke from the other fires will diminish air quality in the Willamette Valley. All locations on the Oregon Coast are likely to experience some smoke and haze. However, much of Central Oregon and Eastern Oregon should experience good air quality, except for some light smoke from LaGrande to Ontario.

Figure 3.  Model-Predicted 24-Hour Average Smoke Concentrations for Tuesday, Sept. 5, 2017

Please refer to the Air Resource Advisor Reports on this blog for more detailed forecasts associated with individual fires. 
Disclaimer: Weather and fire activity can change quickly. Please check back for updates to these forecasts as conditions change. If you’re traveling out of Oregon, many other states also have smoke blogs, including California, Washington, and Idaho. So please consider those resources to help you plan your travels.