Skip to main content

Revised Oregon State Smoke Forecast for Wednesday Aug. 30, 2017

Issued:  August 29, 2017
Forecaster.  R. Graw, USDA Forest Service

Yesterday’s forecast was a bust for the Willamette Valley resulting from the increase in fire activity associated with the thermal trough. The increase in smoke production combined with the delay in the wind shift is now causing unhealthy levels of air quality throughout much of Western Oregon and the Cascades. This is illustrated in Figure 1, which was taken from the morning overpass of the MODIS satellite. The good news, is that stronger, westerly winds are expected to begin around 5 p.m., and should scrub out the air down to the valley floor within a few hours, and air quality should greatly improve later this evening for the Willamette Valley.

Figure 1.  MODIS Satellite Image from Tuesday morning, Aug. 29, 2017

Wednesday - Aug. 30, 2017

An upper level trough advances into the western portion of the state, bringing southwesterly (i.e., from the southwest) winds aloft, ahead of the trough. As the trough advances eastward, the winds will shift, bringing northwesterly winds across much of the state, later in the day.

This pattern will bring relief to the Oregon Coast and the Willamette Valley but transport the smoke from the fires to the northeast during the day, and to the southeast in the evening. Consequently, much of our state will continued to be impacted by smoke. Figure 2 is the Blue Sky model-predicted 24-hour smoke concentrations (in a relative sense) for tomorrow, and Figure 3 illustrates the peak hourly concentrations that may be expected within the forecast period. However, the shift in winds in the evening is not depicted.  

Figure 2.  Model-Predicted 24-hour average smoke concentrations for Wednesday Aug. 30, 2017

Figure 3.  Model-Predicted Maximum 1-Hour Smoke Concentrations for Wednesday Aug. 30, 2017

Disclaimer: Due to rapidly changing conditions, the reliability and accuracy of these forecasts may change. Updates to the forecast will be posted if warranted. As always, please refer to the Air Resource Advisors’ reports on this blog for more detailed smoke forecasts for areas near the fires.