Firefighters in California are confronted with numerous challenges, and now they may have to contend with a rare and perilous phenomenon known as fire tornados. These unique occurrences arise when wildfires generate their own weather patterns, contributing to the complexities of battling rampant flames.
The National Weather Service issued a warning on Tuesday regarding the heightened risk due to a combination of fierce winds and extremely dry conditions. This warning highlights a “particularly dangerous situation” where any new fire outbreak could spread rapidly. While tornadoes were not specifically mentioned in the advisory, meteorologist Todd Hall indicated that, under these severe conditions, the emergence of fire tornadoes is a possibility.
Understanding fire tornados requires clarity on terminology. Commonly referred to as fire whirls, fire devils, or firenados, the terminology can vary among scientists, firefighters, and the general public. Some experts suggest that fire whirls occur solely due to heat, while fire tornados involve clouds influenced by the fire itself. The glossary from the National Wildfire Coordinating Group does not include a definition for fire tornado but describes a fire whirl as a “spinning vortex column of ascending hot air and gases” that rises from a fire, accompanied by smoke, debris, and flames. Notably, substantial whirls can exhibit intensity comparable to a small tornado.
Wildfires featuring turbulent smoke plumes can produce clouds that may result in lightning or a vortex of particles. Leila Carvalho, a meteorology and climatology professor at the University of California, Santa Barbara, explains that the rotation is instigated by intense wind shear combined with a localized low-pressure system created by the heat.
Fire tornados possess the ability to enhance the strength of fires by drawing in more air. Carvalho notes that they generate a designated tornado path, with destruction similar to conventional tornadoes. For example, in 2018, a massive fire tornado, extending the length of three football fields, claimed the life of a firefighter amid a significant wildfire near Redding, located about 250 miles north of San Francisco. Scientists observed an ice-capped cloud that soared seven miles into the atmosphere and triggered winds reaching 143 mph.
Research indicates that fire tornadoes can transport airborne embers, also known as firebrands, leading to fires igniting over vast distances. James Urban, an assistant professor in Fire Protection Engineering at Worcester Polytechnic Institute, notes that such behavior poses hazards not only for first responders but for anyone in the vicinity, as the fire’s movement can unexpectedly change direction.
The formation of a fire tornado is dependent on the interactions among wind, fire plume dynamics, and the surrounding topography. Certain landscapes can create restricted airflow patterns conducive to spiral formations.
In laboratory settings, researchers at Worcester Polytechnic Institute, in collaboration with San José State University, have successfully created small fire tornadoes. Through designing barriers around a fire or strategically placing smaller fires to limit airflow, they are able to simulate these phenomena; however, the scale is significantly smaller than what is seen during actual wildfires. While claiming to possess the largest fire lab in the U.S. at a university level, Urban emphasizes that replicating the magnitude reported in real wildfire situations remains unattainable.
