Tag: weather

Scientific American has produced a video that describes the formation of the fire tornado that burned and scoured a mile-long path as the Carr Fire burned into Redding, California July 26, 2018.

In the video below, click on the little square at bottom-right to see it in full screen.

There were two fatalities on the Carr Fire that day. Redding Fire Department Inspector Jeremy Stoke was burned over in his truck on Buenaventura Boulevard. On the other side of the Sacramento River, on the west side, Don Ray Smith was entrapped and killed in his dozer.

According to a Green Sheet report by CAL FIRE, the conditions that resulted in the entrapment of three dozers and the Redding Fire Department Fire Inspector that day were due to the fire tornado — a large rotating fire plume that was roughly 1,000 feet in diameter. The winds at the base were 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. Multiple fire vehicles had their windows blown out and their bodies damaged by flying debris.

The strong winds caused the fire to burn all live vegetation less than 1 inch in diameter. Peak temperatures likely exceeded 2,700 °F.

The Carr Fire burned 229,651 acres, destroyed 1,077 homes, and killed 3 firefighters and 5 civilians

The news media sometimes calls any little fire whirl a “fire tornado”, or even a “firenado”. 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.”

Thanks and a tip of the hat go out to Rick. Typos or errors, report them HERE.