LOS ANGELES >> Just before 3 p.m. on Wednesday afternoon, as temperatures in Butte County simmered around 106 degrees, a man pushed a burning car down a gully in Chico in what authorities say was an act of arson.

Within minutes, the flaming vehicle ignited tall grasses that had sprung up in the wake of a wet winter but dried out in recent weeks. Soon, live oak trees and grapevine were burning, and wind-driven embers were shooting down canyons and the along ridges of the Lassen foothills, catching new vegetation as they touched down.

By nightfall, the Park fire had grown to 6,000 acres, and by the following morning its size had expanded sevenfold. As of today, the fire had surpassed 307,000 acres — the largest so far this year in California— with no containment and few signs of slowing down.

Experts say the fire’s explosive growth is due to a perfect storm of hot, dry conditions, combustible vegetation and a landscape that hasn’t burned in decades. The remote terrain has made it challenging for crews to gain access to the blaze’s swelling perimeter, and the firefight could be long and arduous as they struggle to gain a foothold.

“This is really the first fire in the past several years in California that I would call extraordinary — and that’s not a good thing,” Daniel Swain, a climate scientist with UCLA, said in a briefing. “This fire is a big deal, and it has done some pretty incredible things.”

Indeed, the fire and its massive smoke plume have already exhibited rare and erratic behavior, including “super-cell thunderstorm-like characteristics” replete with large-scale rotations, Swain said. On Thursday, footage captured by AlertCalifornia wildfire cameras appeared to show the blaze spewing tornado-like vortices, sometimes referred to as fire-whirls or firenados.

“At this point the fire is kind of creating its own weather, and that can be pretty unpredictable,” said Courtney Carpenter, a meteorologist with the National Weather Service in Sacramento. “Really big, explosive wildfires can create thunderstorms; they can make whirling fire plumes that can mimic tornadoes.”

The Park fire’s thunderstorm characteristics haven’t yet sparked lightning — though Carpenter said that’s still possible given its “explosive fire growth” and extreme behaviors. She noted that smoke from the blaze has already reached Oregon.

Fortunately, the fire’s rapid rate of spread has so far marched it north and east — stretching across northern Butte County and a growing portion of Tehama County — into a relatively remote mixture of grass, brush and timber and away from the threatened communities of Cohasset and Forest Ranch. But Swain said it is almost certain to become several times larger than it currently is, and will probably be a several-hundred-thousand-acre fire before it is contained.

“This is a fire we’re going to have with us for weeks, if not months,” he said. “This may be one of those fires that starts in midsummer and burns into mid-autumn … and it could end up posing more of a threat to communities later on.”

The fire has already carved a path of destruction. Chief Garrett Sjolund, of the California Department of Forestry and Fire Protection’s Butte County unit, said “numerous structures” have been burned, including 134 buildings destroyed and an additional 4,000 under threat.

Ignited within Chico’s city limits, the fire has had an overwhelming favorable path, experts said— pushed by dry, southerly winds that moved it away from the city center.

However, officials have been worried about the community of Cohasset, where they initially feared a repeat of the 2018 Camp fire, which razed the nearby community of Paradise and killed 85 people — the deadliest wildfire on record in California. During that blaze, dozens of people were trapped on the area’s limited roadways while trying to escape.

“Cohasset was particularly concerning to us because … there is really only one way out and that is a narrow, windy road,” said Butte County Sheriff Kory Honea. “It is hard to traverse, so we wanted to get those warnings out as quickly as we could.”

About 4,000 residents have been evacuated from Cohasset, Forest Ranch and parts of northeast Chico, along with several rural areas in southern Tehama County.

While the dry winds that drive fire weather conditions in the area typically come from the north, a less frequent pattern brought them from the south this week and sucked up all the Bay Area moisture they usually carry with them, said Carpenter, the weather service meteorologist.

“Things have been really dry for the last month — and hot — and that’s why we’re seeing those critical fire conditions,” she said.

The area was been under a red flag warning, signaling dangerous weather that supports rapid fire grow, both Thursday and Friday.

That pattern has pushed flames into wilderness that has been untouched by fire for decades, if not longer — making it ripe with thicker vegetation and dead and dying brush, which ignites easily and fast.

“There’s tremendous amounts of live and dead fuels,” said Dan Collins, a spokesperson for Cal Fire’s Butte Unit. He added that the Ishi Wilderness area and some parts of Cohasset “have zero to little fire history” on record.

The region’s rugged topography is hampering firefighting efforts, with steep cliffs, expansive canyons and few roadways throughout the national forest.

“That’s one of the big challenges, just getting folks [to the fire lines] due to the remote area,” Collins said.

The blaze isn’t the only Western wildfire of concern. Cal Fire is battling more than 20 active fires in the state, while crews in Canada are combating an 89,000-acre blaze in the Alberta province that has already leveled portions of the historic resort town of Jasper. Experts say many of the fires have been fueled by the persistent, record-setting heat wave that has blanketed the West for weeks.

Residents from the Chico area are watching the Park fire’s movements with anxiety.

“It’s been a pretty restless time for us,” said Don Hankins, a professor of geography and planning at Cal State Chico who is also on the Butte County Fire Safe Council.

The Big Chico Creek Ecological Reserve where he conducts much of his research has already burned, with cameras indicating that nearly all of its infrastructure has been lost, including an 1870s-era barn, Hankins said.

Though the blaze has some echoes of the Camp fire, the community of Cohasset has prepared in recent years for a potential fire, Hankins said, including fuel-reduction projects and prescribed burns to help clear some of the combustible material that lies between the town and the wildland.

“But unfortunately, with the wind on this, and the scale of these projects, it’s not necessarily enough to make a difference” if the fire continues to burn out of control, he said.

The days and weeks ahead are likely to see more acreage added to the fire as crews contend with rugged, volcanic topography and persistent hot and dry conditions.

“The outlook is that it’s not going to be easily contained,” Hankins said. “We’ve got a long season ahead of us before the rainy season comes, and that’s really going to be the ultimate thing to curtail any of these fires that are happening across the West right now.”

Sjolund, the fire chief in Butte County, said he’s hopeful an expected drop in temperatures and increase in humidity this weekend could assist in fighting the Park fire — and others across the region.

“It’s kind of a moving target with the way the weather patterns are coming in,” he said. “This fire is moving very rapidly and very quickly.”

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This Los Angeles Times story was distributed by Tribune Content Agency.