Last weekend, a deadly tragedy struck the Indiana State Fair when the main performance stage collapsed during a freak storm. A witness to the event captured this terrifying moment on video.
After looking at the weather data and videos of the event, at least one meteorologist believes a gustnado may be responsible. So what exactly is a gustnado?
A gustnado is gust storm that forms ahead of a thunderstorm. It's a pocket of powerful, swirling air that extends between 30 to 300 feet high.
A gustnado produces intense wind bursts that can reach up to 80 MPH, as powerful as an F1 tornado. This is powerful enough to uproot trees with shallow roots, knock down billboards and cause minor damage to roofs, chimneys and windows.
Gustnadoes are often confused with tornadoes as both can occur during a thunderstorm. A gustnado forms on the gust front of a thunderstorm, while a tornado forms from a giant rotating thunderstorm called a supercell. Unlike tornadoes, gustnadoes stay on the ground and their vortex does not reach the storm clouds above. Gustnadoes are like whirlwinds and dust devils, but they are more powerful and devastating.
AccuWeather.com Senior Meteorologist Henry Margusity studied the unusual storm that hit the Indiana State Fair last weekend. After looking at radar data and video footage from the fair, he believes the evidence points to a gustnado. You can read his argument here. [Accu-Weather, Weather Savvy via Scientific American]