Issued: Monday Sept.
4 2017
Forecaster. R. Graw, USDA Forest Service
A subsidence inversion, combined with a thermal trough and east
winds will create smoky conditions over Western Oregon on Tuesday, and light to
moderate conditions over Central and Eastern Oregon, respectively.
Forecaster. R. Graw, USDA Forest Service
A significant change has occurred since yesterday’s forecast,
particularly for western Oregon, and to a lesser extent for Eastern Oregon,
prompting an update to today’s forecast. Yesterday’s weather led to several new starts and significant growth on
existing fires. Additionally, the winds overnight carried smoke from active
fires in Oregon, Washington, and Idaho into several portions of the state
including the Willamette Valley, the coast, and eastern Oregon.
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.
Figure 1 illustrates the smoke pattern anticipated for
today. For the western portion of the
state, winds will be out of the east in the morning, then north in the
afternoon. The coast and Willamette
Valley will experience smoky and hazy skies, with the heaviest smoke in
Eugene, Portland, and the Columbia River Gorge. Heavy smoke will continue to be present over southwest Oregon, and the
central and southern Cascades. An east
wind will bring some smoke into eastern Oregon from the fires in Idaho. Central Oregon will experience some of best
air quality relative to other portions of the state.
Figure 1.
Model-Predicted 24-Hour Average Smoke Concentrations for Monday, Sept.
4, 2017
Tuesday Sept. 5, 2017
Figure 2.
Model-Predicted 24-Hour 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.