When people search for a “snow tornado,” they are looking for the name of a swirling column of snow that resembles a funnel cloud. This spectacular phenomenon is a genuine vortex of wind that appears in cold, snowy environments, but it is not a true tornado in the meteorological sense. Understanding the precise name and mechanism of this winter event clarifies why it is dramatically different from a destructive tornado.
The Correct Terminology
The accurate meteorological term for the common swirling snow column is a “Snow Devil.” This name places it in the same category as a dust devil or steam devil, which are all localized whirlwinds driven by surface-level heating. Colloquially, this event is sometimes referred to as a “Snownado,” a portmanteau that simply describes its visual similarity to a tornado.
A Snow Devil is a vortex composed entirely of snow particles and ice crystals lifted from the ground. It is not a condensation funnel that descends from a cloud, which is the defining characteristic of a true tornado. The phenomenon is essentially a column of snow raised from a snow-covered surface by a rapidly rotating column of air.
The Mechanics of Formation
The formation of a Snow Devil requires a specific and relatively rare combination of atmospheric conditions. The process begins with a significant temperature contrast near the surface, such as very cold air passing over a comparatively warmer patch of ground or a frozen lake. This temperature difference causes the warmer air to rise quickly.
As this warm air ascends, it creates an updraft, which is the initial step in forming a vortex. Low-level wind shear then acts upon this rising air. This shearing effect causes the updraft to begin rotating, forming a whirling column of air.
The vortex gains visibility as it sweeps across the snow-covered ground, picking up loose, dry snow particles. These particles are lifted high into the atmosphere. Snow Devils are typically small in scale, averaging between 15 and 30 feet in diameter and reaching heights of 40 to 50 feet. Their short lifespan, often lasting only a few seconds to a couple of minutes, also contributes to their rarity.
Distinguishing from True Winter Tornadoes
A Snow Devil is different from a true tornado, often called a winter waterspout or landspout. The Snow Devil is a non-supercell phenomenon, meaning it is not generated by a rotating thunderstorm. Its rotational energy comes from thermal and wind differences at the ground level, not from a large-scale atmospheric storm system.
True winter tornadoes are rare but do occur, forming from a vertically developed, rotating cloud system known as a mesocyclone. These events require warm air advection and significant atmospheric shear to create a large, destructive funnel. For example, a genuine tornado with a confirmed EF1 rating and 90 mph winds was recorded in Southern Ontario, Canada, in 2013, despite the precipitation being entirely snow.
True winter tornadoes are destructive systems that pose a serious threat to life and property. By contrast, a Snow Devil is a harmless, localized whirlwind that only lifts snow, similar to a dust devil in its weak intensity. The difference in scale is dramatic, as a true tornado can be hundreds of yards wide and travel for miles, whereas a Snow Devil is a fleeting, miniature event.