The Oregon Department of Environmental Quality today issued an air quality advisory because smoke from fires in the Cascades is drifting through stagnant, cloudless skies into the Willamette Valley.
DEQ says its advisory will be in place until Friday as record-breaking heat persists. Temperatures at Portland International Airport reached a record 85 degrees yesterday, marking a record seventh day in October with a high above 80 degrees, according to meteorologist Jeff Forgeron at KPTV.
“Smoke from wildfires burning in the nearby areas, combined with forecasted conditions, will cause air quality to reach unhealthy levels at times through Friday,” DEQ said in a statement.
Among the late-season blazes in the Northwest is the Nakia Creek Fire, which has burned 70 acres of grass and brush near Larch Mountain, according to the Washington Department of Natural Resources.
The culprit behind the unseasonable warmth and August-like fires is a stubborn high-pressure ridge parked over the Northwest that is blocking storms that would otherwise be arriving from the Pacific at this time of year, according to the National Weather Service.
Portland will get a short break from smoky skies this afternoon as a disturbance in the upper atmosphere brings lower temperatures and winds from the west, the NWS says on its website. The high-pressure ridge is expected to return after that and persist at least until Friday.
The ridge has been a feature of Northwest weather recently. It lasted so long in 2013 that it got a name: the Ridiculously Resilient Ridge. Dr. Daniel Swain, a climate scientist at UCLA, coined the term on his California weather blog and cited it as the cause of California’s extraordinary drought that year.