Issued: Aug. 30, 2017
Forecaster. R. Graw, USDA
Forest Service
The upper level trough will move out of the state on Thursday,
and a ridge of high pressure will begin to build in on Thursday and remain
throughout the weekend. This will bring
the return of hot, dry weather, and the associated increase in fire activity
and smoke production. Assuming we don’t
get any new fire starts, the smoke will continue to affect the areas which have
been inundated with smoke already -- Southwestern Oregon, the Cascades, and the
eastern slope of the Cascades from Klamath Falls north to Redmond. Other areas will be affected depending upon
transport winds, as described below.
Thursday Aug. 31, 2017
A northeast wind will occur on the west side of the Cascades,
which will keep smoke out of the Willamette Valley, and all but the southwest
coast. The Columbia Gorge and Mountain
Hood National Forest will also have good air quality. Unfortunately, the Rogue Valley is not likely
to see a significant improvement in air quality, but could see periods of
lighter smoke. Light northerly winds
will occur in Eastern Oregon, which will likely experience some light smoke and
haze, caused by smoke coming down from the fires in Central Washington. The areas of heavier smoke are shown in
Figure 1 as indicated by the darker and medium shades of red in the Figure 1.
Figure 1.
Model-predicted 24-hour average smoke concentrations for Thursday Aug. 31, 2017
Friday - Sept. 1, 2017
Fire activity is expected to increase today with the return of
hot and dry weather. Smoke will begin
moving into the south and eastern portions of the Willamette Valley on Friday,
but not affect the entire valley (that comes later in the weekend). The smoke from the Horse Prairie fire will
affect the coastal areas southwest of this fire. Southwestern Oregon, including the Rogue
Valley will be on the receiving end of smoke from the High Cascade
Complex. The east side of the Cascades
will experience an easterly wind pushing smoke from the Milli, Whitewater, and
Falcon fires back towards the west, affecting mountain communities on the west
side of the Cascades down to Eugene. By
afternoon the east wind in Central Oregon will bring hazy skies to nearly all
of Western Oregon, and could mix down to the surface elevating smoke levels
throughout the Willamette Valley.
Saturday - Sept. 2, 2017
Another hot and dry day is expected with elevated levels of fire
activity. The day will begin with winds
out of the east in western Oregon and out of the south and southeast for
central and eastern Oregon. This will
transport smoke into Western Oregon including the Willamette Valley and the
Coast from the fires in the Cascades, but bring some relief to the communities
on the eastern foothills of the Cascades such as Redmond and Bend. However, in the afternoon, a reversal of
wind direction is expected, in western Oregon bringing some relief to the
coast. These westerly winds will gradually extend across the Cascades and into
central Oregon by early evening, bring the smoke back into the communities on
the eastern foothills of the Cascades. Unfortunately, this will only bring some minor relief to the Willamette
Valley and the wind speeds do not look very strong, and may not be sufficient
to scour out the smoke.
Sunday - Sept. 3, 2017
The day will begin with light northerly winds in Western Oregon
and westerly winds over central and eastern Oregon. Wind speeds will be increasing throughout
the day, beginning in the Columbia River Gorge extending to Pendleton, followed
by increasing westerly winds along the eastern foothills of the Cascades, by
afternoon, and extending across much of the state, including western Oregon by
early evening. This will likely help
scour smoke out of areas many areas but also increase fire activity. Thus, the smoke should clear out of the
Willamette Valley by night. Eastern
Oregon will experience some light smoke and haze as the smoke from the fires in
the Cascades in transported eastward.
Please refer to the Air Resource Advisor Reports 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.