The Dixie fire burning in Butte and Plumas counties mushroomed to more than 100,000 acres Thursday, becoming the second California blaze this year to surpass that acreage milestone.
The aggressive fire has now destroyed at least eight structures, the California Department of Forestry and Fire Protection said, and at least 1,500 more are threatened as it continues its slow crawl east toward Lake Almanor.
The fire was at 103,910 acres and 17% containment Thursday morning, according to Cal Fire, which had no update on the blaze's spread or containment on Thursday evening.
It is the second fire in the state this year of that size. Days ago, the Sugar fire in Plumas National Forest garnered the designation when it grew to 105,000 acres.
The Sugar fire and a nearby blaze, the Dotta fire, have been grouped together as a single incident — the Beckwourth Complex — which as of Thursday afternoon remained at about 105,000 acres with its perimeter 98% contained, according to fire officials.
Wind and topography also played a role in the Dixie fire's latest run, said Cal Fire Butte County spokesman Rick Carhart, as the area's valleys, peaks and canyons are enabling erratic movement and spread.
"There are fingers of fire that are burning, so it's not the whole fire front moving together," Carhart said. "With more flame-front out there, there's more ability for it to grow."
Carhart said clear skies forecast for Thursday afternoon would encourage fire activity because it "allows more sun onto the fire and heats things up."
An additional 500 firefighters and support personnel have arrived to help fight the flames, bringing the total size of the crew to just over 3,900, he said. Firefighters have come from Colorado, New Mexico, Arizona and even Florida to help with the operation.
The Butte County Sheriff's Office has issued evacuation orders for Lake Almanor's west shore, as well as portions of Butte and Plumas county. About 3:30 p.m., the Sheriff's Office also ordered evacuations in the town of Paradise along McCann Drive, Royal Meadow Lane and Sunnyside Lane.
Evacuation warnings have also been issued in Butterfly Valley, the Round Valley Reservoir and Long Valley, the Chester area and the Lake Almanor Peninsula. The Sheriff's Office issued an evacuation warning for Paradise residents on Neal Road south to Little Dry Creek.
Several road closures are in place, including portions of Bucks Lake Road and Highway 89, according to the California Department of Transportation.
The Pacific Crest Trail is closed between Quincy-LaPorte Road and Highway 36 near Chester. Hikers are advised to leave the trail south of Quincy-LaPorte Road and rejoin in Lassen National Park, the Pacific Crest Trial Assn. said.
During a community briefing Wednesday evening, Cal Fire operations chief Tony Brownell said crews were contending with 40-foot-tall flames, noting that spot fires were increasingly jumping containment lines.
"If conditions hold, we've got a great probability of success up here," he said, but "Mother Nature gets a vote. If the wind comes back up, we get spots over the line."
Conditions are similarly challenging at the Tamarack fire in Humboldt-Toiyabe National Forest, which swelled across the California-Nevada state line for the first time Wednesday afternoon.
By Thursday evening, the fire had burned 50,129 acres and was only 4% contained, according to the U.S. Forest Service. It was believed to have been sparked by lightning on July 4, about 16 miles south of Gardnerville, Nev.
Fire incident spokeswoman Tracy LeClair said the focus Thursday remains near the junction of Highways 88 and 89, as well as along Highway 395, where the fire is most active and poses a potential threat to the communities of Spring Valley and Holbrook Highlands.
More than 1,200 personnel are working to quench the flames, she said, including ground crews, helicopters and air tankers.
"Across the fire, it's really very hot, dry and windy," she said, "and on the east side — because of the change in fuels down to piñon, sage and grasses — it's been very fast-moving and very dangerous."
The Alpine County Sheriff's Office ordered mandatory evacuations for the Blue Lakes Road area and the Mesa Vista area. Previously issued evacuation orders in Markleeville, Grover Hot Springs, Shay Creek, Woodfords and nearby areas remain in effect.
The Douglas County Sheriff's Office in Nevada has issued voluntary evacuations for all residents in the Topaz Ranch Estates and Topaz Lake areas. Previously issued evacuation warnings in the Leviathan and Holbrook Junction areas are unchanged.
Portions of Highway 88 remained closed Thursday because of the fire, Caltrans said.
Highway 395 is closed from China Springs Road to the Nevada-California state line. Sheriff's vehicles have stopped escorting residents along the highway because it is unsafe to do so amid the worsening fire.
This story originally appeared in Los Angeles Times.