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Oregon State Smoke Forecast for Labor Day Weekend, 2017

Issued:  Aug. 31, 2017 (revised at 8:30 pm)
Forecaster.  R. Graw, USDA Forest Service

For the Labor Day weekend, the situation is dynamic. Near record temperatures are expected for much of the state, allowing for increased fire activity and smoke production. The southwestern portion of the state, and Cascades Mountains will continue to experience heavy smoke. Smoke will continue to affect other parts of the state at times, as described below. Eastern Oregon is likely to be least impacted by smoke over the holiday weekend.

Friday Sept. 1, 2017

Winds will transport smoke primarily to the southwestern portion of the state throughout the day on Friday, as shown in Figure 1 below. Afternoon mixing will allow smoke to lift away from the surface giving some relief during part of the day. Central Oregon should get a break from the smoke today, once the inversion breaks in late morning. The coast and Willamette Valley should also stay smoke free for the day. Eastern Oregon should experience good air quality throughout the day. Brookings, Gold Beach, the Applegate and Rogue valleys and the southern portion of the Cascades will experience the worst smoke.   

Figure 1.  Model-predicted 24-hour average smoke concentrations for Friday Sept. 1, 2017

Saturday - September 2, 2017

Very hot and dry weather is expected as a thermal ridge moves into the state. This will continue to dry out fuels and cause increase fire activity with the associated instability, thus causing more smoke.  East winds will occur in western Oregon bringing smoke from the Cascades all the way to the coast, as illustrated in Figure 2 below. The entire Willamette Valley will see some smoke, with the heaviest concentrations in the southern portion of the valley.  However, Central and Eastern Oregon will be relatively smoke free except for some possible light smoke or haze moving in from Idaho and Washington. Klamath Falls may get some light smoke as well from the Jade Creek fire near Lakeview.

Figure 2.  Model-predicted 24-hour average smoke concentrations for Saturday Sept. 2, 2017 

Football Forecast:  Saturday afternoon, September 1, 2017

Because we love our football here in Oregon, here’s the forecast for Saturday afternoon. Oregon State is taking on Portland State beginning at 11 a.m. in Corvallis, and Oregon is taking on Southern Utah in Eugene at 5:15 p.m. The figure below is the model-projected three-hour average smoke concentrations ending at 2 p.m. (11 a.m. - 2 p.m.) on Saturday. Sorry Duck fans, that’s as far out as I can project right now. Moderate amounts of smoke are expected in both locations during game time.  A revised forecast will be provided tomorrow morning, with the new model run.

Sunday - Sept. 3, 2017

The thermal ridge will migrate to the central and eastern portion of the State on Sunday, giving some relief from the east winds which also bring smoke into the western portion of the State.  Areas of western Oregon including the Willamette Valley will start out smokey, but begin to clear as the day progresses.  The southern Oregon Coast will be similar - starting out smokey but clearing throughout the day. Unfortunately, southwest Oregon will remain smokey throughout the day.  A northwest wind will occur over the Cascades transporting smoke from the fires into central Oregon. A north wind will be present over central and eastern Oregon pushing the smoke to the south. Good afternoon mixing is expected which may help dilute some of the smoke in the central portion of the state.

Monday - September 4, 2017

The day will  be marked by a transition in smoke transport on the west side of the Cascades.  The most pronounced difference will occur in Roseburg and south, where the morning will start out with east winds and smokey,  but clearing in the afternoon as winds shift and come from the west.  In the southwest part of the state, the coast will start out smokey, but should clear in the afternoon with the wind shift.   The Willamette Valley will experience winds out of the north, keeping much of the valley smoke free.  The Cascades will see an east wind most of the day, keeping smoke present east of the fires most of the day.  In central Oregon, the winds will be out of the north in the morning but shift to the east in the afternoon.  The east wind will likely keep Bend, Redmond, and Sisters free of smoke most of the day, after the morning temperature inversion breaks.  The east side of the state will start out with a north wind, but shift to the east in the afternoon.  This will result in relatively good air quality most of the day on Monday.

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.