A Yosemite National Park fire that started Sunday has burned almost 4,500 acres and is about 5% contained, officials said Tuesday.
The fire has spread quickly and in multiple directions. Eight helicopters and 327 firefighters are helping suppress the flames, including crews from the National Park Service and U.S. Forest Service. The effort has cost $100,000 to date.
Park officials are still investigating the high-elevation wilderness fire's cause. They think it is a spot fire from a lightning-caused burn, dubbed the Meadow fire, which started in mid-July.
Around 185 hikers were evacuated by helicopter on Sunday night, including 85 from the Half Dome summit and 100 from trails and campgrounds in Little Yosemite Valley, where the fire spread to both sides of the Merced River between Half Dome and Mt. Starr King.
Officials previously estimated the damage at nearly 2,600 acres. Park Ranger Ashley Mayer said fire surveyors used infrared mapping Monday night to get a more accurate picture of the affected area. As a result, she said, not all of the 1,900-acre increase can be attributed to the fire's spread.
Additionally, Mayer said, there are granite outcroppings within the 4,500 affected acres, so most but not all of the damage is burnt trees. She said firefighters are using natural barriers such as granite rocks to contain the blaze, instead of removing trees and creating a containment line.
"We want to leave that wilderness area in its natural state," she said.
Mayer said the weather in Yosemite Valley is warm but not too windy. The National Weather Service forecast shows Wednesday could get slightly warmer, with a high of 84 degrees and wind gusts as high as 15 mph.
More smoke crept into the valley on Tuesday than was apparent on Monday. Mayer said visitors should expect to continue seeing smoke in the coming days.
Several trails and camps are closed until further notice, including:
Little Yosemite Valley
John Muir Trail between Little Yosemite Valley and Long Meadow
All routes on Half Dome, including the cables, NW Regular Route and Snake Dike
Sunrise and Merced Lake high sierra camps and backpackers' camps
Sunrise Trail south of the Tenaya Lake Trail junction
Clouds Rest, Sunrise Lakes, Emeric Lake and Babcock Lake
Bridalveil Creek Campground (to house firefighters)
Trails and camps in the area that remain open include:
Mist, John Muir and Panorama trails to the top of Nevada Fall
Vogelsang Backpackers' Camp
Tenaya Lake Trail
Fletcher Creek Trail between Vogelsang and Merced Lake Ranger Station
All park roads, entrance stations, and facilities are open. Park officials said visitors should check the park's website to get updated air quality information.