In Redding rubble, signs of giant tornado-like vortex
Damage not typical of fire
REDDING, Calif. — As authorities sifted the rubble from the fire that burned more than 1,000 residences in Shasta County, they were startled by what they encountered.
A soaring transmission tower was tipped over. Tiles were torn off the roofs of homes. Massive trees were uprooted.
Vehicles were moved. In one spot, a fence post was bent around a tree with the bark on one side sheared off.
This was not typical wildfire damage. Rather, it was strong evidence of a giant, powerful, spinning vortex that accompanied the Carr fire on July 26. The tornado-like condition, lasting an hour and a half and fueled by extreme heat and intensely dry brush as California heats up to record levels, was captured in dramatic videos that have come to symbolize the destructive power of what is now California’s sixth-most destructive fire.
It may take years before scientists come to a consensus on what to exactly call this vortex — a fire whirl, as named by the National Weather Service, or a fire tornado. Whatever it’s called, it’s exceptionally rare to see a well-documented fire-fueled vortex leap out of a wildfire and enter a populated area with such size, power and duration.
It’s believed to have lasted from 7 p.m. to 8:30 p.m. on July 26 and struck some of the hardest-hit neighborhoods in Redding.
This kind of fire twister has been documented before, but only a handful “at this sort of scale,” said Neil Lareau, assistant professor of atmospheric sciences at the University of Nevada, Reno, who was among those comfortable calling it a fire tornado. “You’re starting with a rare event to begin with, and for it to actually impact a populated area makes it even rarer.”
The National Weather Service on Thursday said a preliminary estimate of maximum wind speeds in the vortex were in excess of 143 mph. That would make it equivalent to a twister with a rating of EF-3 out of a maximum of 5 on the Enhanced Fujita scale.
“Depending on the final number, this might actually be the strongest ‘tornado’ in California history, even if it wasn’t formally a tornado,” UCLA climate scientist Daniel Swain said by email. There have been a couple of marginal EF-3 twisters in California’s past, “but this fire whirl was almost certainly longer-lived, larger in spatial scope and perhaps even stronger from a wind speed perspective.”
It’s too early to say whether the vortex contributed to the deadly ferocity of this blaze, which killed six. But with climate change playing a factor as California enters a worsening era of wildland fires, last week’s fire vortex adds a layer of unpredictability and danger.
“Not all big fires are going to result in these big fire whirls, even in a future that’s much hotter and drier,” Swain said. “This won’t be the primary risk associated with wildfire ever. But under the right atmospheric conditions, all else being equal, the increasing intensity of fires themselves will play a role in producing these localized fire weather conditions that can be quite extreme.”
Radar analyzed by Lareau clearly shows a spinning vortex in northwest Redding as the Carr Fire rapidly expanded in the evening of July 26.
Lareau roughly estimated the vortex as being as perhaps 500 yards in diameter at its base before possibly contracting. “It’s covering blocks,” he said.
“It was definitely a massive one, and that just speaks to how intense the heating was,” said National Weather Service meteorologist Mike Kochasic. “It created such a massive whirl that it looked like a tornado … and it takes an impressive amount of heating and local wind swirling up to create something like that. It was quite a monster.”
It’s possible for fire vortexes to “move fairly quick out in front of the main line of the fire — it can spread a little bit quicker compared to the main fire,” Kochasic said.
Wind damage was also reported in areas untouched by flames.
A team of officials led by the California Department of Forestry and Fire Protection is looking into the vortex as part of its investigation of the blaze.
This vortex is dramatically different from the garden-variety whirls that have been more of a curiosity in past fires, which are more like dust devils in terms of scale, rising for perhaps two stories and lasting for less than 10 minutes.