On August 11 we wrote about an impressive fire whirl (or fire tornado) that occurred on the Sam Fire in northwestern Los Angeles County August 10. Thankfully a helicopter from KTLA 5 was airborne and got compelling video, including a water drop from an Air-Crane helicopter that at least for a few seconds took most of the energy out of the rapidly rotating vortex of flame.
Here is the video:
Unfortunately the video stops immediately after the water drop so it is unknown if it regenerated.
In describing the event, we wrote, “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.”
Now we know who made the drop.
Erickson’s Pilot in Command flying the Air-Crane that is seen dropping water, Ed Montgomery, was quoted in Erickson Incorporated’s Twitter feed, @EricksonInc. Below is the text from a series of six tweets:
What I can tell you is that those types of situations are very intense, for not only the aircraft on the fire but also for the firefighters that are on the ground. Fire tornadoes can and often do throw fire balls out in front of the fire and the threat in this particular instance, was that the highway was the fire line, and the tornado was approaching the highway. If it had been allowed to advance it would have certainly spotted fire across the highway and turned a 140 acre fire into a much larger incident.
We were fortunate to have had N163AC as our aircraft – it has our new composite blades installed and we were at the last quarter of our fuel cycle. This means we were able to pick up 2,300 gallons of water for that drop.
As you can see from the video, fire tornadoes create a tremendous amount of inward air flow to its core. All I really needed to do was get in front of it while it was in the open, be away from the heat column, and high enough for the tornado to suck the entire water drop into its core.
The phenomenon was either a fire whirl or fire tornado. It is difficult to tell from the video the width or height of the vortex. It appears not to be huge, but the speed of the rotation was extremely swift and the area influenced by the strong indrafts was very large. At the one minute mark check out the spot fires that ignite and instantly grow much larger as they are drawn toward the vortex.
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.
Technically not a tornado. Weather event generated from the sky downward. OR, sometimes seemingly connected from ground to sky in a pyrocumulonimbus system.
This one seems to have super fast rotation, and the distance it’s drawing from is impressive as heck
Hi Bill, Just this morning at a coffee, one of the fellows described a relative’s experience with an unquestionable tornado. It ‘cut’ a path it created through a corn field. A relatively narrow swath of corn plants were torn out of the swath leaving bare ground with a sharp edge. And the corn plants, puller out of the ground, were found dropped some distance from this swath.
The fire whirl (dust devil) is easy to explain. The tornado is not. It begins in the atmosphere far above the surface. It is easy to observe its ‘funnel’ shaped cloud as it narrow bottom end wiggles back and forth. It is easy to explain how the whirling atmosphere creates a central low atmospheric pressure volume. But from where does any lifting action of this central low pressure atmosphere come?
I do not pretend the following is original but it is hard to find and read. My proposed lifting action is the Bernoulli Principle which explains the lifting action of an airplane’s wing’s shape. Steven Ackerman and John Knox, in their textbook (Meteorology 3rd. Ed) page 186. in Figure 6-6 image and caption get what I consider close to explaining how an atmospheric tornado could be created. I read the caption: “The 500-mb isobaric chart for the Christmas 2009 blizzard” and I stop here because I cannot, in this comment, show a reader the chart.
What I can point out is that a broad near westerly jet stream at the 500-mb level, can by the Bernoulli Principle, lift the atmosphere beneath it as shown in the chart. But as I have stated, I have not found anyone, suggesting a similar chart might exist during a spring, summer, or fall season to create a much more localized tornado or thunderstorm.
Have a good day, Jerry
I can assure you that the drop I made had a positive effect on the Fire Tornado and allowed fire fighters on the ground to secure the fire line at the highway and resulted in the total fire area to be minimized.
Captain Ed Montgomery
Erickson AirCrane
Ed, I, for one, didn’t doubt that for a second. On the contrary, I was quite proud of you. The residual effects following the drop no doubt subsided as the convection column’s heat dissipated. The video cut off too soon to see the vortex entirely gone. You, no doubt, saw what the video missed.
Nothing but respect, Captain Montgomery. What an amazing sight that must be. Awesome skills on display as well. Nice shot!
Any estimate on height/width? The in-feed fire lines must have been impressively long! Hundreds of feet?
Is this the first time you’ve done a drop in a large rotation like that? If I missed that, my bad.
I know it’s a terribly dangerous, potentially destructive situation but it’s also endlessly fascinating and to get a closeup like that is truly a one in a million situation. Glad you and others were unharmed.
These pilots deserve so much more recognition for their work on fires…we’d be screwed without them
One can see active vortex patterns of smoke from “doused” shrubs in the last few frames, but that doesn’t mean that they weren’t indicative of death throes.
I have seen very small fire whirls form on the edges of Rx burns; I wonder whether or not the relatively hottest spots create enough more vertical velocity to initiate them, and as the rate of convective rise sucks more heat into them, depriving the “cooler” areas of heat and making the convection column stronger, and a compounding of the heat creates a “vicious” cycle?
Yes, it took cojones for the chopper jockey to split that hair.
Another local news helicopter ABC7’s: Their video is a bit clearer, but it also cut-off too fast. I find myself Monday morning quarterbacking those cameramen, but they aren’t thinking of tactics and fire behavior so much https://www.youtube.com/watch?v=pJ81-CsuxRM