Smoke expected to lift Sunday over Washington fires, possibly attracting explosive fire growth

Matt Demiter, of the Everett Fire Department, runs his hand through gravel and ash to check the ground temperature while working with crews to stomp out long burning embers remaining after a wildfire near Okanogan, Wash., on Saturday, Aug. 22, 2015. (Ian Terry /The Herald via AP) MANDATORY CREDIT (The Associated Press)

In this photo taken on Friday night, Aug. 21, 2015, Gold Bar fire Lt. Scott Coulson keeps an eye on a wildfire in the hills outside of Omak, Wash., as wildfires continue to burn throughout north-central Washington. (Genna Martin/The Herald via AP) MANDATORY CREDIT (The Associated Press)

In this photo taken on Friday evening, Aug. 21, 2015, Gold Bar fire Lt. Scott Coulson investigates brush fires in the hills outside of Omak, Wash., as wildfires continue to burn throughout north-central Washington. (Genna Martin/The Herald via AP) MANDATORY CREDIT (The Associated Press)

The latest on wildfires in Washington state, including those that killed three firefighters (all times local):

10:30 a.m.

Fire officials in Washington state say a complex of wildfires burning in north-central Washington has grown to cover 374 square miles. Infrared mapping found the fires spread about 19 square miles Saturday evening.

Fire spokeswoman Suzanne Flory says there could be some explosive fire growth Sunday if a cap of smoke lifts from Okanogan County, as has been forecast. When the smoke lifts on a wildfire, humidity drops, heat rises and fires can flare up. Flory says it's similar to what happens when the flue is opened on a fireplace.

Flory says the good news is that less smokes means restrictions on air travel will be lifted and more fire tankers can fly over and drop water and chemical retardant.

Meanwhile, county officials have downgraded some evacuation notices, allowing some people to return to their homes. 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. She says some people have been getting in the way of firefighting operations.

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9:30 a.m.

A new firefighting mobilization center 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.

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

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.