JACKSON, Wyo. — For those wondering where the haze that’s settled in Jackson Hole is coming from, the answer is wildfires to the west of the valley.
The smoke from several large wildfires blazing in eastern Oregon, central Idaho and southern Montana is blowing east and settling in the valley, according to Brett McDonald, Meteorologist with the National Weather Service in Riverton, Wyoming.
The western U.S. is currently under a high pressure system whose center is hovering around southern Utah. High pressure systems move in a clockwise direction, so winds north of Utah are blowing east, bringing smoke into western Wyoming, says McDonald.
There are currently several large fires contributing to the smoke blowing east into western Wyoming. The quickly growing Bench Lake Fire near Stanley, Idaho was at nearly 1,300 acres as of the morning of Tuesday, July 18, according to InciWeb, the government site that tracks wildfires. The Horse Gulch Fire in southern Montana near Helena has reached over 1,300 acres and is 10% contained, and the Cow Valley Fire in eastern Oregon has been dubbed a “megafire” at over 133,000 acres, with only 16% contained.
“The ongoing wildfires have been burning more actively in recent days due to hot temperatures and strong wind gusts from thunderstorms, which have led to fire growth and greater volumes of smoke being produced,” said Buckrail Meteorologist Adam Smith.
Air quality in the valley was rated at moderate as of 12 p.m. on July 16, according to the government’s AirNow map. This rating means that sensitive people should reduce outdoor activity and go inside if they experience symptoms.
Residents of Jackson Hole can expect to keep seeing this smoke in the air until Thursday, July 17, when the high pressure system is predicted to shift to a low one and winds will start to blow the smoke farther north, according to McDonald.
In the meantime, haze will probably be worse in the mornings.
“Heavier smoke can sometimes become ‘trapped’ in the valleys during the morning hours when temperature inversions are present, meaning cool dense air sinks to the valleys with warmer air aloft preventing the air from rising and dispersing,” says Smith. “Inversions typically erode by mid-morning during the summer months as the sun quickly heats up the valleys.”
