SAN FRANCISCO (CBS SF) — Once considered an natural oddity, columns of towering flames known as a ‘firenado’ packing 100 mph-plus winds have become an increasingly common threat over the last four years as the wildfires that have ripped through Northern California have gained in intensity.

Fire tornadoes — firenadoes, fire whirls — occur when intense rising heat and turbulent wind conditions combine to form whirling eddies of air. These eddies can contract into a tornado-like vortex that sucks in burning debris and combustible gases.

On Monday night, a firenado was recorded on video as the Lava Fire grew in intensity and was quickly expanding from 5,000 acres to 13,300 acres.

Veteran federal hotshot firefighter Aaron Humphrey has witnessed first hand the destructive power of a firenado. He was part of a federal hotshot fire team that battled the deadly 2018 Carr Fire.

He watched in horror as a firenado obliterated entire neighborhoods. It still haunts the former hotshot supervisor.

“You are in a fog and expecting death or disaster around every corner … It collectively killed my hotshot spirit,” Humphrey, 44, said of the fire tornado.

Atmospheric scientist Neil Lareau, an assistant professor in the Physics Department at the University of Nevada, studied the Carr firenado.

The phenomena spun to life on July 26, 2018 between 7:30 p.m. and 8 p.m. and was packing winds of an estimated 143 mph — the power of an EF3 tornado.

The firenado weather system topped out at 17,000 feet above the Earth’s surface as it scorched through a widespread area of Redding, devastating everything in its path. It was related to four deaths, a number of injuries and the destruction of many homes.

During last September’s deadly Creek Fire, officials said two firenadoes spun to life during the blaze’s advance in the Sierra National Forest.

Officials said the intense heat of the fire, fueled by thousands of dead trees, created its own weather system and sent a pyrocumulus cloud soaring thousands of feet into the sky.

Federal forecasters said one of the firenadoes was rated an EF-2, with winds up to 125 miles per hour. The other had winds of up to 100 miles per hour and was rated an EF-1. Both took place on Sept. 5th.

Firenados In California Wildfires

  • Massive Creek Fire Spawned Two Firenados During Advance In Sierra National Forest
  • ‘Firenado’ Spotted As Hog Fire Scorches 8,000 Acres In Northern California
  • Weather Service Issues Rare Firenado Warning For Wildfire Burning Near Loyalton
  • Scientists Find Causes Behind Redding ‘Firenado’ During Carr Fire
  • Woodward Firefighters Encounter Fire Whirl While Battling Marin County Wildfire
  • The Creek Fire firenadoes wreaked havoc across the rugged area, the result of “unprecedented fire behavior,” government forecasters said.

    “To have even one tornado within a fire is rare,” CNN meteorologist Taylor Ward said. “Fires can lead to fire whirls — kind of like a dust devil — due to differential heating, but to get a tornado with winds of over 100 mph is quite unusual.”

    The firenadoes uprooted pine trees, snapping even several 2-foot diameter trees and stripping bark from their trunks, a storm survey report said.