MADISON COUNTY, Ind. – Severe storms caused damage across central Indiana on Monday knocking over large trees and knocking out power. As the storm passed through Madison County, authorities received damage reports that consisted of down trees and power lines, as well as power outages.
While the original thought, by the Madison County Emergency Management Agency & Department of Homeland Security Office, was a tornado caused this damage, it has been determined, by the National Weather Service Office in Indianapolis, that a ‘gustnado’ was observed.
What is a gustnado?
A gustnado is a relatively small whirlwind that forms as an eddy in the outflow of a thunderstorm. They do not connect with any cloud-based rotation and are not tornadoes, even though damage associated with them can be similar to weak tornadoes.
Gustnadoes form due to non-tornadic straight line wind features in the downdraft region of a thunderstorm, specifically within the fust front of strong thunderstorms. They tend to be visible when the vortices loft sufficient debris or form condensation clouds, as was the case on Monday.
The gustnado was observed in Madison County when it formed over Aqua Garden Lake on the leading edge of the severe thunderstorm Monday morning. It moved onto land in a northeast direction for about one mile. Straight line winds also caused damage to the east.
The National Weather Service Office in Indianapolis wants to remind everyone that while it is important to note that although this was not classified as a tornado, gustnadoes can produce damage consistent with a low EF-0 to EF-1 tornado or roughly in the 65-80 mph range.