The Incredible Science Behind the Carr Fire’s “Firenado”

Photo by Cody Markhal

The people of Shasta County are certainly used to wildfires. During fire season every year, scores of residents are evacuated from their houses, with most people lucky to never see their houses destroyed. But when the 100-foot wall of flames of the Carr Fire hit the area, no one could have prepared for the consequences.

It was the first time anyone in the area had seen the devastation of a giant “Firenado” or fire vortex. And while the erratic winds aided to the intensity of the fire, it was not exactly the cause of what the untrained eye would see as a “tornado filled with fire.”

In fact, scientists are saying that the flames became so intense from hot weather and dried out areas that it created its own weather system.

“This is not what I would call a wind-driven fire,” U.S. Forest Service meteorologist Tom Rolinski told the Los Angeles Times. “It’s more of a plume-dominated fire. It creates a lot of erratic fire behavior.”

The heat sucks out all the moisture out of plants and brush, and when the triple degree heat of the afternoon creates an unstable atmosphere above the fire plume, the collapse of the clouds creates a dangerous downdraft for everything on the ground.

“Wind damage in Redding suggests that fire-induced vortex may have behaved similarly to full-fledged tornado,” UCLA Climate Scientist Daniel Swain. “Mature trees uprooted, roofs peeled off, high-tension power pylons down, & windows smashed.”

So think about it this way: when the fire sucks the oxygen out of the dry plants, the force of that suction create gusts of winds. When the fire gets so intense, the winds pick up around the flames, creating a self-sustaining tornado of flames and destruction.

Below you can see an illustration of the fire vortex that occurred in the Carr Fire on July 26, with the black line showing the vortex center from the surface. The vortex is nearly upright and extends to over 5 kilometers, creating the tornado visual:

The years of a punishing drought have finally created a dangerous situation during fire season in Northern California. But no one foresaw the gigantic and terrifying flames of the Carr Fire as the end result.

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