Scores of wildfires across the western US have belched so much smoke that it is helping firefighters gain ground on the biggest blaze, the Bootleg fire in Oregon, by blocking sunlight, officials said on Saturday.
Both the National Weather Service (NWS) and officials with the Oregon Department of Forestry said smoke in the lower atmosphere from California wildfires has floated over the Bootleg fire, which has scorched more than 401,000 acres in Oregon, about 250 miles south of Portland.
“It’s called ‘smoke shading’ and it’s basically put a lid on the lower atmosphere for now, blocking sunlight and creating cooler, more stable surface conditions,” said Eric Schoening, a meteorologist with the NWS in Salt Lake City.
The phenomenon is unpredictable and the area is still under red-flag warnings from the NWS, which said the Pacific north-west may experience high temperatures and wind gusts that can fan flames and spread sparks and embers. Schoening said the weather was a “mixed bag” in terms of helping firefighters.
Marcus Kauffman, a spokesman for the forestry department in Oregon, said the drawback of the “smoke shade” was that it made it harder to fly planes and helicopters that drop water and chemical fire suppressants.
More than 2,000 firefighters and support crews had contained about 42% of the Bootleg fire by Saturday, although the fire jumped containment lines the night before, Kauffman said, adding: “We lost 1,600 acres.”
The Bootleg fire is one of more than 80 large wildfires in 13 states that have charred about 1.3m acres, an area larger than Delaware, according to the National Interagency Fire Center (NIFC) in Boise, Idaho. The Bootleg fire has destroyed an area half the size of Rhode Island.
The smoke has been carried by the jet stream and other air currents as far as New York and Boston, where some have felt contamination in eyes, noses and lungs.
Climate change has made the west much warmer and drier and will continue to make weather more extreme and wildfires more frequent and destructive.
In Montana, five firefighters remained hospitalized after a thunderstorm and swirling winds blew a lightning-caused wildfire back on them, federal officials said.
The five had joined other crews working on the 1,300-acre Devil’s Creek fire in rough, steep terrain near the town of Jordan. The firefighters were building a defensive line when the weather shifted, said a Bureau of Land Management spokesperson, Mark Jacobsen.
Jacobsen declined to release the extent of the firefighters’ injuries. The firefighters included three US Fish and Wildlife Service crew members from North Dakota and two US Department of Agriculture Forest Service firefighters from New Mexico.
On Saturday, Governor Greg Gianforte announced that fire crews from California and Utah were coming to Montana to help.
In California, Governor Gavin Newsom issued a state of emergency for four northern counties because of “conditions of extreme peril to the safety of persons and property”. The proclamation opens the way for more state support.
The Tamarack fire south of Lake Tahoe had burned more than 92 square miles of timber and head-high chaparral of mostly national forest land, fire officials said.
The fire, sparked by lightning, destroyed at least 10 buildings and forced the evacuation of more than 2,400 homes. That included about 1,300 ordered evacuated for the first time on Thursday when blowing embers ignited a new spot fire that jumped US Highway 395 north of Topaz Lake on the California-Nevada line.
Pat Seekins, operations section chief for the Rocky Mountain incident management team, said they were shifting significant resources. More than 1,300 firefighters were battling the overall fire, and more resources were on their way.
Seekins said the spot fire “grew very large” very quickly. It had burned an estimated 10 square miles.
“We had a really active day yesterday. It was pretty severe,” he said. “It’s going to take a lot of work. That will be a very high priority for us today.”
Mandatory evacuation orders were issued Friday in Butte county, California, as the Dixie fire continued to grow explosively eastward, becoming the state’s largest fire this year. On Thursday, officials in Plumas county in the Sierra Nevada west of the Nevada line also ordered evacuations.
The fire had burned more than 223 square miles as of Friday evening, officials said. It destroyed at least eight buildings and threatened at least 1,500 more.