Dear Tom,
What is a gustnado? I have heard the word, but do not understand its meaning.
—Valerie Worsten, Lombard
Dear Valerie,
A gustnado is a brief surface-based vortex that forms within a surge of air blowing out of a strong thunderstorm. Most gustnadoes last from a few seconds to occasionally, a few minutes. They form as eddies within otherwise straight-line wind flow and as such, despite the name, are not related to tornadoes. Gustnadoes typically produce winds near 50 mph but occasionally become a bit stronger and may be capable of causing minor damage to structures, but injuries are very rare. Strong thunderstorms contain powerful downdrafts that, when striking the ground, spread outward and cause a rush of wind at the surface. If there is sufficient instability, a gustnado might form.