As night fell on the Missoula Valley Wednesday, the air quality remained unhealthy – not only because of a half-dozen nearby wildfires, but also because of fires burning in California, Oregon and Idaho.
And conditions won’t be any better by morning, said Sarah Coefield, an air quality specialist with the Missoula City-County Health Department.
In fact, Missoula’s air quality was the worst it’s been all year on Wednesday. And its closest wildfires continued to burn actively, with the Lolo Peak fire becoming such a threat that new evacuations were ordered by the Ravalli County sheriff.
“It was a miserable day,” Coefield said, “but at least we could all be miserable together.”
A strong ridge of high pressure kept a lid on the valley, creating a stable atmosphere that prevented the abundant smoke from moving out of the city’s breathing space.
There was hope for some mixing in the afternoon, but that didn’t materialize in Missoula. There was some improvement during the afternoon in Lolo, Seeley Lake and Florence, Coefield said, but the air there also remains unhealthy.
In Frenchtown, Arlee, Evaro, the Swan Valley and Clearwater Junction, the air quality is unhealthy for sensitive groups – children, the elderly, and people with heart or lung diseases.
Coefield provided a copy of Wednesday afternoon’s satellite photo, which showed a good deal of cloud cover, but also revealed the direct path of wildfire smoke from Oregon, California and Idaho to Missoula.
“Southwesterly flow aloft is delivering the smoke to western Montana, and it’s going to be putting a damper on air quality conditions across the region until the overhead wind direction shifts,” she said. And that’s not going to happen for at least two days.
In the meantime, there will be new layers of smoke from the local wildfires, particularly the Lolo Peak fire south of Missoula.
Late Wednesday, the Ravalli County sheriff ordered new evacuations because of the fire’s aggressive burning on its southeastern front. The updated evacuation order area includes all residents on Sweeney Creek Loop north of and including Outback Road to include Woodtick Hollow, Sweeney Creek Trail, Upper Sweeney Creek Loop, Hill Drive, Koepplin Lane and Smith Fork.
Thursday morning’s air quality forecast called for continued widespread smoke. Conditions will deteriorate to hazardous in Florence, Lolo and Seeley Lake because of their proximity to the active wildfires.
There’s a chance “for a good scouring” starting Thursday afternoon, according to Coefield and the National Weather Service. “A cold front will move through the area, and winds should start picking up shortly after noon.”
The NWS is predicting sustained 20 mph winds, with gusts to 30 mph. That’s good for air quality, but bad for fire activity – which would, of course, produce more smoke.
Passing thunderstorms also could produce some lightning, according to the forecast, and that – of course – could ignite new wildfires.
The more stable, polluted conditions are expected to return on Friday and through the weekend, with worsening air quality as smoke continues to build up in the valleys.