A wildfire burns on the south side of Lake Chelan across the lake from the town of Manson, Wash., Friday, Aug. 21, 2015.

Image Credit: Alan Berner/The Seattle Times via AP

TWISP, Wash. - The massive cloud of smoke is expected to lift over Washington wildfires on Sunday, but as air quality improves fire behaviour could become more erratic and intense, fire officials said.

"It's like a flue opening in a fireplace," explained Suzanne Flory, spokeswoman for the U.S. Forest Service and the Rocky Mountain Incident Management Team. "Smoke serves as a cap on the fire."

The Okanogan Complex of wildfires was measured at 374 square miles Sunday morning, after growing more than 100 miles larger Saturday in what fire officials said was a relatively calm fire day.

Sunday was expected to be a different story. Once the smoke lifts, humidity drops, heat rises and fires flare up.

The complex of fires was estimated to be about 10 per cent contained as of Sunday morning, according to fire spokesman Dan Omdal.

Containment does not mean the fire has stopped burning. It means it has run out of fuel to burn in that area, either because it has hit a man-made fire line, a retardant drop, a road or a lake.

Some of the land within the fire lines is still burning, but other sections have burned out.

"We call it a wildfire, but much of the fire has been tamed," Omdal said. "We are making progress,"

The good news for Sunday is that less smoke means restrictions on air travel will be lifted and more fire tankers can drop water and chemical retardant, Flory said.

Air quality, which has been dangerously bad, will also improve when the smoke cloud lifts, but firefighters won't be able to take a breather.

"We tell firefighters, if you see blue sky, heads up," Flory said.

Meanwhile, local officials have downgraded some evacuation notices, allowing some people to return to their homes. Thousands remain under evacuation notices.

Sarah Miller, a spokeswoman with Okanogan County Emergency Management, says residents have been warned to stay ready to leave at any time and to not drive around looking at the fires.

"People driving around are getting in the way of fire operations," Miller said.

Steve Surgeon, a mechanic and scrap metal seller who lost everything he owns except for his home on the outskirts of Okanogan, said he was just happy to be alive.

He stayed in place as the fire raced over a ridge and barrelled down toward his home, flames lapping just feet from his back porch.

"I'm alive," he said with a sigh Sunday. "I shouldn't be, but I am and that's what matters."

Heaps of twisted and charred metal litter his land where the fire burned through. Surgeon estimates he lost more than $100,000 worth of property, including his shop, his motorcycle, several cars, a travel trailer and all of his tools.

Steve Surgeon surveys the ruins after he lost everything he owned except his home in a wildfire on the outskirts of Okanogan, Wash., Sunday, Aug. 23, 2015.

Image Credit: AP Photo/Brian Skoloff

"But I have my life and I have my home," he said. "Everything else can be replaced."

Surgeon didn't have any insurance to help cover the cost of what he lost and was hoping the federal government would eventually offer assistance.

"But all my titles to everything were in the shop and that's burned to the ground," he said. "I guess I'm just going to stay and just try to slowly rebuild."

Meanwhile, a new firefighting mobilization centre is being set up at Fairchild Air Force Base near Spokane to help fight wildfires in Washington state. The base will be the staging area for 20 large fire engines and 10 water takers and will be run by a team from San Diego, California.

The new firefighting resources come one day after the Obama administration approved Washington Gov. Jay Inslee's request for a federal emergency declaration to help firefighting efforts in the eastern part of the state.

The new fire engines are coming from Utah, Nevada, Arizona and Colorado, Inslee's office said.

Sixteen large wildfires are burning across central and eastern Washington, covering more than 920 square miles. More than 200 homes have been destroyed and more than 12,000 homes and thousands of other structures remain threatened.

More than 1,000 people were fighting just the Okanogan Complex of fires on Sunday.

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Blankinship reported from Seattle.

News from © The Associated Press, 2015