Watch: 'Firenado' forms along California's Park Fire
There was no severe weather in sight, but the intense heat from the Park Fire created its own weather system — a swirling menace of a vortex that was a surreal mix of wind, smoke and flames.
'Firenado' swirls over Northern California's Park Fire
Weather Command breaks down how massive wildfires, such as the Park Fire burning near Chico, California, can create its own tornado-like vortex.
CHICO, Calif. — Amid a raging wildfire that has burned homes near Chico, California and scorched over 160,000 acres, cameras picked up yet another frightening sight along the fire lines: a "firenado".
There was no severe weather in sight, but the intense heat from the Park Fire created its own weather system — a swirling menace of a vortex that was a surreal mix of wind, smoke and flames.
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"These fire-generated vortices form in an environment where spin and shear is present," said FOX Weather Meteorologist Bob Van Dillen. "Now, with regular tornadoes, rising air is typically caused by major weather systems… differential heating at a low pressure center." Cold air aloft allows for warmer air near the surface to rise, creating convection and storms.
'Firenado' swirl spotted amid raging Park Fire in Northern California
The "firenado" was spotted in Butte County, California as the rising air from the wildfire's heat draws in surrounding air to twist into a swirling vortex.
But in a fire tornado's case, development is triggered by the intense heat along the surface and a massive rush of rising air.
"Think about the differential heating times about 100," Van Dillen said. "You have tremendous amounts of heating going on right here."
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And as air rushes in to replace that rising air, the column can begin to rotate if there is enough wind shear present.
The National Weather Service’s Doppler radar located near Oroville captured the spinning winds Thursday evening, giving a radar signature that looked more at home in Tornado Alley.
Park Fire Radar image showing a velocity scan Wednesday evening indicating a tornado-like vortex along the Park Fire. The green colors indicate winds heading toward the radar while bright red indicate winds moving away.
"You’ve got wind going in one direction; you’ve got wind going in the opposite direction right next to each other," Van Dillen said. "That to me looks like what it would be with an actual supercell tornado that’s forming… So that was a fire tornado as it rolled though. (Steven) Spielberg couldn’t come up with something like that."
Aside from the dangers of being near a fire-infused vortex, fire tornadoes can toss embers far away from the current footprint, sparking new fires outside containment lines.
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EF-3 equivalent fire tornado struck Redding in 2018
The most daunting fire tornado happened during the massive Carr Fire that struck Northern California in July 2018. Fueled by widespread flames burning around the town of Redding, the intense heat created a fire-generated pyrocumulus cloud that stretched 40,000 feet high, triggering supercell-like storm dynamics that eventually spawned a vortex with winds estimated at over 140 mph.
A similar strength tornado would correspond with an EF-3 rating on the Enhanced Fujita Scale.
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There were no reports of any injuries or additional damage from the Park Fire fire tornado. But the Park Fire has burned "numerous" homes so far, officials said. More than 4,400 people have evacuated and over 1,100 firefighters are on the scene battling the blaze.
Investigators say the cause of the fire was arson, and a suspect is in custody.