Update: Washburn Fire in Yosemite National Park tops 2,000 acres as hotter weather looms

UPDATE: 6:40 P.M.: The Washburn Fire, churning through heavy dead and downed fuels, has now burned more than 2,000 acres in Yosemite National Park.

A warming trend starting Monday will present hot and dry conditions through at least the end of the week.

“It will be actively spreading,” a Yosemite Fire spokesperson said.

The fire is listed at 2,044 acres with 0% containment. The cause remains under investigation.

Wawona Road (Highway 41) is still closed from the south entrance to Henness Ridge Road, Mariposa Grove also is closed until further notice.

All other areas of Yosemite National Park remain open via highways 140 or 120. Reservations are still required.

UPDATE 1:15 P.M.: Some of the latest mapping of the Washburn Fire in Yosemite National Park indicates a growing area of more than 1,800 acres, an increase of more than 50% since Saturday afternoon.

A map from the National Interagency Fire Center, based on satellite detections of fire hot spots, shows that the fire is now at 1,815 acres as of midday Sunday, but fire information officers at the park said they were unable to confirm that estimate. Early Sunday, the acreage was reported at just under 1,600 acres, compared to 1,190 acres by early Saturday evening.

UPDATE 12:30 P.M.: As crews battled the growing Washburn Fire near the south entrance to Yosemite National Park, a small fire broke out Sunday at Mirror Lake near the Yosemite Valley, fire officials with the park confirmed shortly after noon.

The Mirror Fire was estimated at about one to two acres and is being fought by a crew of firefighters as well as a bucket helicopter to drop water on the fire, said Nancy Phillipe, a fire information spokeswoman for Yosemite National Park. The cause of the fire has not been determined.

The Mirror Fire is about 17 miles north of the Washburn Fire.

PREVIOUS STORY, updated:

The Washburn Fire burning in Yosemite National Park grew to almost 1,600 acres overnight Saturday and Sunday morning, an increase of nearly 50% from Saturday evening.

The most recent reports Sunday morning from the National Park Service and the National Interagency Fire Center indicate that the fire, which started Thursday afternoon along Washburn Trail in the park’s Mariposa Grove of giant sequoias, is burning in challenging terrain in an area with an ample supply of heavy fuel.

The cause of the fire is under investigation.

Saturday saw a significant increase in the resources being devoted to the firefight. About 360 firefighters are working to contain the fire, about 150 more than the previous day. Those include hand crews building containment lines around the fire, along with engine crews, 11 helicopters and aerial tanker planes.

The firefighting cost so far is estimated at about $1.5 million, the national fire center reported.

Despite the additional resources, containment of the Washburn Fire remains at 0%, said Nancy Phillipe, a fire information spokesperson for Yosemite National Park. The fire is expected to grow at a moderate pace, increasing in activity through at least the first half of the week. Rising temperatures are likely to create challenging conditions for firefighters.

“Today the weather is going to be hotter and drier,” Phillipe told The Fresno Bee on Sunday morning. “That dries out the fuels and makes it easier for the fire to spread.”

By midday Sunday, crews were making progress in creating hand lines at the southern edge near the fire’s origin point at Mariposa Grove and along the southwestern edge of the fire, said Matt Ahern, deputy operations chief with the California Interagency Incident Management Team that is coordinating the firefighting effort.

But, Ahern added, the fire is continuing to move westward toward Wawona Road, and “the fire has hit (Wawona Road) for about a quarter or a half mile” west of Mariposa Grove. Elsewhere, spot fires are popping up beyond the fire perimeter “and it’s all moving in a north-northeasterly direction,” Ahern said.

During the hottest parts of the day, embers from the fire have been creating new spot fires at distances up to eight-tenths of a mile beyond the perimeter south of the Merced River’s South Fork. “They’ll get active and they’ll grow together,” Ahern added. “That’s creating the large smoke columns that are visible for many miles.”

In addition to the closure of Mariposa Grove, near the southern entrance to the park, mandatory evacuation orders are in place for the community of Wawona. Ahern said crews are busy creating fire lines next to the enclave and bringing in sprinkler kits to protect structures if the fire approaches.

Wawona Road is closed from the southern entrance to the park from Highway 41 to Henness Ridge Road.

A fire shelter set up in Mariposa on Friday soon after the evacuations were announced was closed Saturday after serving about 10 people, the Red Cross said in a news release.

The community of Yosemite West is accessible from the north via Wawona Road. The rest of the park remains open, with visitors advised to enter Yosemite National Park using Highway 140 from Mariposa or Highway 120 from Manteca, Jamestown, and Groveland.

While the vast majority of the park is still open, Phillipe said air quality in the park is considered “unhealthy” because of smoke from the fire.

Recent years of drought and weakened trees in the Sierra Nevada range on the east flank of Central California’s San Joaquin Valley are among the concerns for firefighters. “Significant tree mortality from 2013-2015 has left significant dead standing and dead fallen fuels,” according to incident commanders with an interagency fire management team. “This also presents significant safety hazards to firefighters.”

Firefighters may eventually be aided by previous fires that have burned in the park. “Fire scars from past fires located approximately one to three miles from the current fire perimeter will assist firefighters in slowing the growth of the fire,” a Sunday summary of the fire conditions stated.

The Mariposa Grove is the largest stand of massive giant sequoias in Yosemite, with more than 500 of the iconic trees. The grove was the first area of what is now Yosemite National Park when President Abraham Lincoln signed legislation in 1864 to protect Mariposa Grove.

Park officials posted video on social media Saturday showing sprinkler systems installed to protect the Grizzly Giant, a 209-foot-tall, 3,000-year-old sequoia described as the second largest in the grove and one of the most photographed.

Within the Mariposa Grove, which continues to be threatened by the fire, Phillipe said park officials opted against wrapping the base of the Grizzly Giant and other giant sequoias with a foil-like retardant material for fear of creating more of a “baked potato” effect if flames did sweep through the area.

The need to protect the grove and residences in the Wawona community has prompted the use of aerial tanker planes dropping fire-retardant chemicals on the fire and bulldozers to help create containment lines – both unusual steps in a park that is largely designated as wilderness, Phillipe said.

Between the air tankers and water-dropping helicopters, “it’s been quite an aerial show over Wawona,” Phillipe said.