The thunderstorm wind gust that toppled the stage at the Indiana State Fair is a common occurrence among thunderstorms, according to a meteorologist at the National Weather Service.
Daniel McCarthy, meteorologist in charge of the National Weather Service in Indianapolis, says it’s part of the life cycle of a thunderstorm reaching maturity.
“New storms developed out ahead just when the gust front developed because of a collapsing storm behind it,” he says. “That just reinforced more cold air and helped that gust front to move out faster.”
Estimated winds at the fair grounds were 60 to 70 mph. That is equivalent to an F-0 tornado – the lowest category for tornadoes on the scale used by the National Weather Service.
“Severe thunderstorm warnings are just as important as tornado warnings,” McCarthy says. “While tornadoes are associated to be more violent, severe thunderstorms can produce winds equivalent to a weak tornado.”
The thunderstorm warning issued at 8:39 p.m. for Marion County on Saturday night called for a line of severe thunderstorms capable of producing quarter size hail and damaging winds in excess of 60 mph while moving east at 25 mph.
According to local storm reports from the National Weather Service, the fatal wind gust happened at 8:49 p.m., 10 minutes after the warning.