the rear-flank gust front of supercell storms, vertical vorticity very likely has its origins in the upward tilting of vorticity that can occur within descending air in the presence of baroclinity. While injuries or deaths are rare from gustnadoes, strong ones can cause damage and they are hazardous to drivers. There is some speculation that a gustnado might have been responsible for the collapse of a stage at the Indiana State Fair on August 13, 2011 which killed 7 people and injured 58. See also Dust devil, whirlwinds that form due to superheated surface layers and stretched vorticity, most commonly on sunny, warm days with light winds Fujita scale Landspout Waterspout References External links Storm Spotters' Handbook: Tornadoes and Other Funnels (Australian Bureau of Meteorology) NOAA/NWS Glossary Severe weather and convection Tornado fr:Tornade#Gustnado