The concept of fire-induced vortices, often sensationalized as “fire tornadoes,” describes a terrifying natural phenomenon where intense heat from a ground fire creates a rapidly spinning column of air. This vortex can draw in smoke, ash, and burning debris, sometimes even containing flames at its core. These events represent one of the most unpredictable and destructive consequences of extreme wildfires, transforming a surface fire into a three-dimensional atmospheric hazard.
Distinguishing Fire Whirls from Pyrotornadoes
The answer to how many fire tornadoes have occurred depends entirely on the scientific definition used, which separates two distinct phenomena based on scale and origin. The term “fire whirl” describes the most common type of fire-induced vortex, which is typically small, short-lived, and driven by surface heat and localized wind turbulence. These whirls are akin to dust devils, often lasting only a few minutes and possessing wind speeds that do not reach the strength of a true tornado.
In contrast, a “pyrotornado” or a large-scale “pyrovortex” represents a far rarer and more intense event, characterized by a massive, sustained rotating column that can cause significant damage. These vortices are not merely surface effects; they are linked to deep, convective weather systems created by the fire itself. True pyrotornadoes can reach diameters of hundreds of meters and produce wind speeds comparable to an EF-2 or EF-3 rating on the Enhanced Fujita Scale. The destructive vortex observed during the 2018 Carr Fire in California, for example, was scientifically classified as a pyrotornado due to its intensity and duration.
The Atmospheric Mechanics of Pyrovortex Formation
The formation of the most dangerous pyrovortices requires a complex convergence of three specific atmospheric and fire conditions. The first requirement is an extreme and sustained heat release from a large-scale, intensely burning fire, such as a major wildfire. This immense heat generates a powerful, buoyant plume of hot air that rises rapidly into the atmosphere.
The second factor is high atmospheric instability, indicated by a steep lapse rate, where temperature decreases rapidly with altitude. This instability allows the hot air plume to ascend to great heights, creating a massive, localized low-pressure column. This vertical ascent can lead to the formation of a pyrocumulonimbus (pyroCb) cloud, which acts like a fire-generated thunderstorm.
The third ingredient is a source of rotation, usually provided by wind shear or local topographical features like canyons and valleys. As the rapidly rising column of air draws in surrounding air, it concentrates any pre-existing spin through a process known as vortex stretching. The pyroCb cloud helps to sustain this process by releasing latent heat as moisture condenses high up, supercharging the updraft and allowing the vortex to intensify and persist for a sustained period.
Why a Definitive Global Count is Elusive
The question of a precise global count is complicated by the wide spectrum of fire-induced vortices and the limitations of documentation. Small fire whirls, which are common in prescribed burns, industrial fires, and wildfires, are essentially uncountable. Thousands of these minor events occur globally each year, yet they are rarely recorded.
Conversely, the number of documented, large-scale pyrotornadoes is extremely low. These events, defined by their size, intensity, and association with a pyroCb cloud, are scientifically confirmed only through intense post-event analysis of damage paths, meteorological data, and verifiable visual evidence. Unlike traditional tornadoes, which are tracked by weather radar, pyrotornadoes often occur in remote, heavily forested areas, making real-time tracking difficult. Tracking relies heavily on chance, such as high-quality video footage or capture by specialized weather radar, as occurred with the Carr Fire pyrotornado. Due to the difficulty in monitoring remote wildfires and the subjective line between a large fire whirl and a true pyrotornado, a precise, historical global total simply does not exist. The confirmed count of the most powerful, tornado-strength events remains only a handful of cases globally.