Extraordinary weather event: Gustanado

Rarely observed, and even less frequently filmed or photographed due to its very fleeting nature, the gustnado is a tornado that appears to form under the gusts of a storm. A gust front is a flow of very powerful winds that occurs just before the arrival of a storm: these winds rise very suddenly, up to over 100 km/h, and fall almost as quickly after the storm’s arrival of heavy rain. Therefore it is under this gust front that gustnado (contraction) gust front tornado which aptly translates to “gust front tornado”).

Gustanado is often mistaken for a tornado

This phenomenon appears as a vortex, which is quite large and unstructured, which can carry with it some dust and debris from the land.

Most observers would describe this as a tornado, but the difference is that the gustnado is not usually attached to a thunderstorm cloud: it separates from the base of the cloud which is slightly ahead. A true tornado occurs beneath the wall cloud of a supercell, and is associated with it, unlike a gustnado which occurs immediately before the arrival of a thunderstorm cloud (often also a supercell), without being associated with it. On very rare occasions, some observers still describe a gustnado that appears attached to a storm cloud front. Another major difference between tornado and gustnado is their duration. Tornadoes can last from a few minutes to sometimes up to an hour, whereas tornadoes typically last only a few seconds, rarely a minute or more.

Gustanado is rarely dangerous, but disasters have already happened

A gustnado is formed when a stream of cold air from a storm accelerates and descends toward the ground: it touches the ground and is kind of bounced up. It is at this moment that he finds himself facing the warm air of the surroundings which is pulled in by the storm. This mechanism sometimes drives this flow of cold air upward, and then forms a gustnado’s vortex.

It often occurs in isolation, but it happens that several of them are present simultaneously, or they form, die out, then form sequentially. That’s why one storm can generate many grudges. The phenomenon is much weaker than a tornado, but American meteorologists agree that a gustnado must generate gusty winds of at least 93 km/h to qualify for the title.

Due to the short lifespan of the gustnado, damage and injury are rare, but still possible. The most violent gustnadoes generate winds up to 180 km/h, equivalent to an EF2 tornado, while over 320 km/h is possible for an EF5 tornado.

Some gustanados are still responsible for dramatic disasters, mainly in the United States, where they are most common. In August 2011, a fairground in Indiana collapsed, killing seven people and injuring twenty-eight. The event, stormy and turbulent, was so violent and sudden that Gustanado’s hypothesis is the most likely. More recently, in April 2019, a gustnado in Colorado produced wind gusts of 176 km/h, causing damage in the center of town.

In France, gustnadoes are less common than in the United States, South America, and Australia, but it is a safe bet that some of the damage caused by tornadoes is actually the work of a gustnado.