Oregon wildfire creates its own weather as it becomes largest active blaze in US

An immense wildfire in Oregon is now the largest active blaze in the US, and has grown so big that it’s creating its own weather.

The so-called Durkee fire was sparked by lightning and has since grown to nearly 245,000 acres (97,000 hectares). The fire is threatening homes in and around the communities of Durkee, Huntington and Rye Valley, as well as a major highway, cell towers and power infrastructure in the area. Fire crews and equipment from 22 states were battling the blaze.

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Stephen Parker, a meteorologist with the National Weather Service in Boise, Idaho, said the Durkee fire showed such extreme fire behavior on Saturday, Sunday and Monday that it began creating its own weather system with a “pyrocumulus cloud”.

“That can happen when a fire becomes plume-dominated,” Parker said. “It’s like a thunderstorm on top of the fire, generated by the heat of the fire.”

The pyrocumulus cloud allows the smoke and ash from the fire to travel much higher in the air than it would typically, he said. If there is enough moisture in the air above the fire, the pyrocumulus cloud can also generate rain and lightning, potentially causing new fire starts in the region.

The fire is kicking smoke into neighboring states, and fire crews are bracing for a storm late on Wednesday that is expected to bring lightning, strong winds and the risk of flash floods. The Oregon state fire marshal’s office cautioned residents about the risk posed by the storm and the expected “abundant” lightning. The agency has mobilized nearly 500 firefighters to help protect communities that could be threatened by wildfires nearby.

The major electricity utility in the region, Idaho Power, warned customers to prepare for possible outages.

More than 60 significant fires are burning in Oregon and Washington alone, and Oregon has been plagued with hundreds of lightning strikes from thunderstorms that have started new blazes in bone-dry vegetation.

Already, the smoke from the Durkee fire was choking the air in Boise and beyond. An air quality warning was in effect for the entire region on Wednesday.

Patrick Nauman, the owner of Weiser Classic Candy in the small town of Weiser, Idaho, near the Oregon border, said driving into town Wednesday morning was “like driving into a fog bank, because it’s so thick and low to the road”.

“Yesterday you could smell it, taste it, it just kind of hung in the back of your throat,” Nauman said of the smoke.

The Durkee fire is among dozens of wildfires burning across states in the US west including Oregon, Washington, California and Utah. Western states have also spent weeks in the grip of back-to-back heatwaves, some with record-breaking triple-digit temperatures, compounding the risk of new ignitions and creating challenging conditions for firefighters.

Wildfires are also raging north of the border in Canada, forcing the evacuation of one of the country’s largest national parks.

The Pacific north-west has already seen a particularly aggressive fire season . Multiple fires have scorched more than 1,000 sq miles in Oregon, with nearly 180 sq miles torched in the past 24 hours, authorities said.

In central Washington, a fire that sparked on Monday near the town of Naches prompted mandatory evacuations, while another near the town of Bickleton also forced evacuations and threatened a natural gas plant.

“This is shaping up to be another monster fire year in the Pacific north-west, and it’s just mid-July,” Ed Hiatt, the Pacific north-west assistant fire director for operations at the US Forest Service, said on Tuesday in a news release.

Millions of acres of national forest lands across Oregon and Washington are continuing to see record-breaking dry timber conditions, exacerbated by a lack of rainfall, according to the news release.

Related: ‘Fire-breathing dragon clouds’: a wildfire-fueled phenomenon explained

The Oregon governor, Tina Kotek, earlier this month declared an “extended state of emergency” until October because of the increased risk of wildfires.

Elsewhere, a series of lightning-sparked wildfires near the California-Nevada border forced the evacuation of a recreation area, closed a state highway and threatened structures on Tuesday. Nearly 200 children and staff at a summer camp near Portola, a town about 50 miles (80km) north-west of Reno, were evacuated.

Heatwaves and historic drought tied to climate change have made wildfires more challenging to fight in the American west. Scientists have said the climate crisis has made the region much warmer and drier in the past 30 years and will continue to make the weather more extreme, and wildfires more frequent and destructive.

Read more on wildfires in the US west and Canada

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• US government urged to declare wildfire smoke and extreme heat major disasters

• California wildfires have burned five times the average area this year, officials say