Parts of Kentucky and four other states were flattened over the weekend by a string of monster tornadoes that killed dozens of people.
The destruction raises a question for all who are seeing the scenes of destruction: Could a similar string of twisters form where I live?
John Allen, an associate professor of meteorology at Central Michigan University, has an answer that should help calm people in Tampa Bay.
“In North Florida, up towards Tallahassee, you can see high-end tornadoes with some regularity,” Allen said. “But the further south you go, the less of a chance there is. If you’re in Miami, you don’t have anything to worry about.”
The reason: The region’s lack of a strong wind shear. The peninsula’s proximity to the jet stream keeps it away. And in general, no wind shear means no tornadoes.
“It’s really the opposite of what you want with hurricanes, where wind shear is a good thing,” Allen said. “Tornadoes need it to form.”
This is true for much of the year, anyway, until the start of the six-month Atlantic hurricane season June 1. As hurricanes or tropical systems approach, National Weather Service offices in Melbourne, Miami, Tallahassee and Ruskin begin issuing tornado bulletins.
When tropical systems move onshore, they can trigger the formation of strings of tornadoes, Allen said.
“You may not get the really high-end tornadoes, but Florida is susceptible to getting a large number of tornadoes up to EF2 intensity along with tropical systems,” Allen said, “and that’s more than enough to kill someone or cause significant damage.”
Among the six categories of tornado intensity on what’s known as the Enhanced Fujita scale, EF2 means winds of 111 mph to 135 mph.
Allen says twisters that form along these weather fronts often do so in clusters. That’s a big reason why Florida is No. 3 among all states for the average number of tornadoes each year at 66, even though few cause significant damage. Texas with 155 and Kansas with 96 average more.
North Florida is likely due for a major tornado outbreak after barely dodging twisters in recent years, Allen said. This is especially true now as the Pacific Ocean phenomenon known as the La Niña pattern has kicked into gear. La Niña creates a more favorable atmosphere for tornadoes to develop in Florida.
Along with overlapping hurricane season, Florida has another tornado season from January through March. The last major tornado outbreak to hit the state was in February 1998, when 42 people were killed and 260 injured along the Interstate 4 corridor.