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Oregon State Smoke Forecast for Wed-Thursday September 6-7, 2017

Issued:  Monday September 5, 2017
Forecaster.  R. Graw, USDA Forest Service

High pressure and subsidence inversion and east winds continue to dominate our weather for Tuesday.  Fire activity has increased as expected and smoke conditions are very baed over much of the state, particularly in western Oregon as depicted by this morning’s satellite image as shown in Figure 1.  Ash has been reported falling in many areas, including the Portland/Vancouver metropolitan area primarily due to the fires in the Columbia River Gorge.  

Figure 1.  Satellite Image of the Smoke Over Oregon on Tuesday Morning.

Wednesday September 6, 2017

The thermal trough will move to east side of the Cascades on Wednesday, resulting in a reversal of winds in western Oregon.  This will result in improved air quality  in the the central and northern portions of the coast and the Willamette Valley.  The day will start out a bit smokey in much of the state as illustrated in Figure 2. 

Figure 2.  Model-Predicted 3-Hour Average Smoke Concentrations for the period 7-10 am on Wednesday, September 6, 2017

However, smoke will start lifting out of many areas by noon and conditions will improve as illustrated in Figure 3.  While the Cascade Mountains will continue to be smokey from the Washington to California Board, much of southeastern Oregon is expected to be free of smoke.  By  afternoon, some smoke is expected in the northeastern portion of the state from Prineville to Ontario. The Dalles will also experience relatively heavy smoke from the fires in the Columbia River Gorge.  

Figure 3.  Model-Predicted 3-hour Average Smoke Concentrations for Wednesday September 6, 2017 ending at 2 pm.

By tomorrow evening, smoke will move into many communities in central Oregon but clear out of eastern Oregon, as shown in Figure 3 below.  The central and northern coast and the Willamette Valley south to Roseburg should be free of smoke.

Figure 3.  Model-Predicted 3-Hour Average Smoke Concentrations for the Period 6-9 pm, Wednesday, September 6, 2017.