Impressive fire whirl on the Sam Fire in LA County

Fire whirl on the Sam Fire in LA County, Aug. 10, 2022
Fire whirl on the Sam Fire in LA County, Aug. 10, 2022. KTLA-2

On Wednesday afternoon the Sam Fire burned nearly 150 acres of grass and brush in northwestern Los Angeles County. No structures were damaged and there were no reports of injuries.

The KTLA Channel 5 helicopter captured some interesting video of an impressive fire whirl. It’s hard to appreciate it from seeing still photos since it did not appear to be very tall like many large fire whirls, but the indrafts it created are fascinating. At the end of the video below, an Air-Crane helicopter dropped water that at least for a while took most of the energy out of it.

Fire whirl on the Sam Fire in LA County, Aug. 10, 2022
Helicopter drops water on a fire whirl on the Sam Fire in LA County, Aug. 10, 2022. KTLA

Maybe a helicopter pilot can tell us how ballsy it was, or was not, to fly close enough to drop water on the fire whirl.

Fire whirls, much like dust devils, are not uncommon on a fire when the atmosphere is unstable, and are much smaller than fire tornados. In 1978 a researcher for the National Weather Service in Missoula, David W. Goens, established parameters for the two.

He said the average size of a fire whirl is usually 33 to 100 feet, with rotational velocities of 22 to 67 MPH.

But a fire tornado dominates the large scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 MPH.

 

Thanks and a tip of the hat go out to Pat.

PBS explains how fire whirls and fire tornados form

PBS Weathered Firenado
Still image from PBS Weathered. “Firenado: when two of nature’s deadliest forces combine.”

PBS has published a 10-minute video (below) about how fire whirls and fire tornados form. Here is how they summarize it:

A fire tornado, or “firenado,” is exactly what it sounds like: a tornado made out of fire… and it is truly the stuff of nightmares. The most famous example occurred when the 2018 Carr Fire spawned an EF3 fire tornado with estimated wind speeds of 143 mph! And as climate change drives increasing wildfires around the planet, it only makes sense that we see more fire tornadoes as well.

Tune into this episode of Weathered to learn what the latest science can tell us about these rare but dangerous phenomena as well as about the surprising ability of burnt forests to store carbon and mitigate climate change.

Weathered is a show hosted by meteorologist Maiya May and produced by Balance Media that helps explain the most common natural disasters, what causes them, how they’re changing, and what we can do to prepare.

Fire whirls, much like dust devils, are not uncommon on a fire when the atmosphere is unstable, and are much smaller than fire tornados. In 1978 a researcher for the National Weather Service in Missoula, David W. Goens, established parameters for the two.

He said the average size of a fire whirl is usually 33 to 100 feet, with rotational velocities of 22 to 67 MPH.

But a fire tornado dominates the large scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 MPH.

TBT: firefighters caught in fire whirl

For Throwback Thursday, here is what we published on May 20, 2014 about firefighters being caught in a fire whirl:

Fire whirl, 1989
Still image from the video below of firefighters being overrun by a large fire whirl in California in 1989.

You may have seen the footage in the video below, of firefighters being overrun in 1989 by a very large fire whirl or fire tornado (or firenado) in California. It is very impressive, and can be another reason why firefighters need to be on their toes and very situationally aware.

Thanks and a hat tip go out to Kent

Fire whirl filmed with infrared camera

infrared video of fire whirl
Screen shot from infrared video of a fire whirl. Courtesy of RPX Technologies.

Jim O’Daniel of RPX Technologies sent us the link to the video below which shows a small fire whirl filmed by one of their HyperSight infrared thermal cameras. The devices, which can see through smoke, can be mounted on a fire engine.

Mr. O’Daniel said, “The camera we developed is intended as a safety tool for escaping and navigating through smoke. The camera is vehicle-mounted and always ready. It allows the driver to see while keeping windows up and both hands on the wheel.”

And, just to be clear, it is not a “fire tornado”. David W. Goens of the Missoula office of the National Weather Service explained what a fire tornado is:

These systems begin to dominate the large scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 MPH.

In addition, they can last for an hour or more and have been known to move across the terrain for miles. You do not want to be anywhere near a fire tornado. They can be deadly.

After the Carr Fire at Redding last year, a report was issued about a real fire tornado that was related to the death of at least one firefighter.

A large fire tornado was one of the primary causes of the entrapment and death of FPI1 on July 26, 2018. The fire tornado was a large rotating fire plume that was roughly 1000 feet in diameter at its base. tornado Fujita scaleWinds at the base of the fire tornado reached speeds in the range of 136-165 mph (EF-3 tornado strength), as indicated by wind damage to large oak trees, scouring of the ground surface, damage to roofs of houses, and lofting of large steel power line support towers, vehicles, and a steel marine shipping container within ½ mile of the entrapment site. The strong winds caused the fire to burn all live vegetation less than 1 inch in diameter and fully consume any dead biomass. Peak gas temperatures likely exceeded 2,700 °F.

Impressive fire whirl in Australia

fire whirl
A still image from the video below of a fire whirl in New South Wales, Australia, February, 2019.

This video, below, of extreme fire behavior was posted by Shane Fitzsimmons, the Commissioner of the New South Wales Rural Fire Service in Australia. It shows a fire whirl, sometimes incorrectly called a fire tornado. Fire tornados exist, but they are much, much larger and can last for up to an hour or so and average 100 to 1,000 feet in diameter with rotational velocities up to 90 MPH.

Fire whirl recorded on video in the UK

Fire Whirl
Fire Whirl — Leicestershire Fire & Rescue Service

I don’t often associate extreme wildland fire behavior with the United Kingdom, but firefighters with the Leicestershire Fire and Rescue Service grabbed some video of this impressive fire whirl near Swadlincote, a town in Derbyshire, England.

Fire Whirl

Fire Whirl
Fire Whirl — Leicestershire Fire & Rescue Service

We have written about similar phenomenons several times on Wildfire Today. Here is an excerpt from a 2016 article, “Defining fire whirls and fire tornados”:

The news media sometimes calls any little fire whirl a “fire tornado”, or even a “firenado”. We found out today that these and related terms (except for “firenado”) were, if not founded, at least documented and defined in 1978 by a researcher for the National Weather Service in Missoula, David W. Goens. He grouped fire whirls into four classes:

  1. Fire Devils. They are a natural part of fire turbulence with little influence on fire behavior or spread. They are usually on the order of 3 to 33 feet in diameter and have rotational velocities less than 22 MPH.
  2. Fire Whirls. A meld of the fire, topograph, and meteorological factors. These play a significant role in fire spread and hazard to control personnel. The average size of this class is usually 33 to 100 feet, with rotational velocities of 22 to 67 MPH.
  3. Fire Tornadoes. These systems begin to dominate the large scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 MPH.
  4. Fire Storm. Fire behavior is extremely violent. Diameters have been observed to be from 1,000 to 10,000 feet and winds estimated in excess of 110 MPH. This is a rare phenomenon and hopefully one that is so unlikely in the forest environment that it can be disregarded.”