Raining ash in Idaho? Idaho’s air quality worsens this week as wildfire smoke chokes Boise
If you thought Boise’s air quality couldn’t get much worse, you’re wrong.
The National Weather Service in Boise received reports on Tuesday morning of ash raining down from the sky in the west Treasure Valley, including in Weiser, Nampa and the west side of the Boise Bench.
The Treasure Valley has spent most of July under a blanket of smoke as the Cow Valley and Durkee Fires in eastern Oregon continue to rage. The Cow Valley Fire is 78% contained, but the Durkee Fire continues to grow just west of Interstate 84 and has been responsible for sending heavy smoke across the Gem State over the past week.
The rapidly growing Durkee Fire and its associated smoke has been made worse in recent days by strong easterly winds pushing thick plumes of smoke toward Boise.
The Idaho Department of Environmental Quality issued its first red-level air quality advisory of the year on Tuesday. The advisory, labeled as “unhealthy” and the fourth-highest advisory level out of six, warns that children, older adults and people with heart or lung disease should avoid prolonged or heavy exertion.
But how did it get so bad that ash falls from the Treasure Valley sky?
Raining ash from above in Idaho
It’s highly unusual for ash to fall from the sky if an area isn’t near an active wildfire or, in most cases, the fallout from a volcanic eruption.
However, multiple conditions were just right on Monday and Tuesday to allow the Durkee Fire to produce “pyrocumulus clouds,” National Weather Service meteorologist Stephen Parker told the Idaho Statesman on Tuesday.
“It was what’s called extreme fire behavior yesterday,” Parker said. “That’s when the fire becomes plume-dominated, and we were so unstable (in the atmosphere) that the fire was able to basically create its own thunderstorm overhead and create pyrocumulus clouds.”
The scorching temperatures in the fire can take the ash and loft it high into the atmosphere, Parker said. From there, the hot air condenses and forms clouds, but the ash is still trapped inside at a much higher elevation than usual.
Typically, ash would fall in close proximity to the fire. But pyrocumulus clouds allow the ash to drift far away from the fire’s source before finally falling onto unexpected people below.
How long will the air quality be bad in Boise?
If you’re someone who struggles with bad air quality… tough news.
Parker said he expects smoke conditions to get worse before they get better.
“The latest information is we’re going to stay like this pretty much the most of (Tuesday), but tonight into (Wednesday) should get even worse,” Parker said. “By Thursday, we should be getting better for at least a little while, but these forecasts only go about 48 hours because it is a very hard thing to predict.”
Weather Service meteorologist Josh Smith said the best chance for thunderstorms this week is Wednesday night, which would help push smoke out of the Treasure Valley. There’s only a 20% chance of storms for Boise, but 70 mph wind could accompany brief heavy rain and small hail.
On Wednesday, Treasure Valley’s air quality could sometimes creep into the purple “very unhealthy” category. The “very unhealthy” category warns that children, older adults and people with heart or lung disease should avoid all outdoor activity, while everyone else should avoid prolonged or heavy exertion.
Michael Toole, regional airshed coordinator for the Idaho Department of Environmental Quality, told the Statesman that a red air quality advisory is likely, but worse air quality at times isn’t out of the question.
“We could see hourlies in the purple,” Toole said. “The forecast itself is over a 24-hour period, so the way that the air quality index and the forecast work is for particulate matter such as smoke, and we forecast for the entire 24-hour period. So basically, we’re saying over this 24-hour period, here’s what we expect it to average out to.”
This story was originally published July 23, 2024 at 11:59 AM.
