Forecaster: R. Graw, USDA Forest Service
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.
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.