Wildfires in California

Photo: The Canadian Press

Merced and Mariposa County Sheriff's Office members attend a briefing during a wildfire in Mariposa County, Calif., Tuesday, July 18, 2017. Tall grass from a deluge of winter rains is fueling wildfires throughout the Western U.S., damaging more than a dozen homes in Nevada and threatening hundreds more structures in California.

Tall grass from a deluge of winter rains is fueling wildfires throughout the Western U.S., damaging more than a dozen homes in Nevada and forcing residents from communities on the outskirts of Yosemite National Park in California, authorities said Tuesday.

Yosemite remains open to visitors, but flames threaten more than 300 homes and buildings in mountain communities southwest of the park, clearing out the small town of Mariposa.

The fire burning since Sunday also puts at risk powerlines providing electricity to the park, and it has closed roads travelled by tourists, officials said.

Gov. Jerry Brown on Tuesday declared an emergency, bolstering the state's resources to battle the fire that he said has forced thousands of residents to flee and is expected to continue burning.

Record rain and snowfall in the mountains this winter was celebrated for bringing California's five-year drought to its knees, but it has turned into a challenge for firefighters battling flames feeding on dense vegetation, officials said.

"There's ample fuel and steep terrain," said California Department of Forestry and Fire Protection spokeswoman DeeDee Garcia. "It makes firefighting difficult."

Smoke from the fire in Mariposa County has drifted more than 150 miles away to Reno.

In a remote northeastern corner of Nevada, roughly 14 homes were damaged or destroyed by a wildfire that started Monday. Officials have lifted an evacuation advisory, allowing hundreds of people to return home and assess damage, authorities said.

In Nevada, wind is driving the flames through invasive cheat grass — growing twice the norm, U.S. Bureau of Land Management spokesman Greg Deimel said.

"It is very thick, very dense," he said. "You get the winds and the density of the grass, the fire just goes."

This summer's high temperatures follow a very wet winter that dumped more than 60 feet of snow at ski resorts in the Sierra west of Reno.