UPDATED Wednesday, Oct. 16, to include the latest information from the National Weather Service Miami Office on the number of South Florida tornadoes.
The rash of violent tornadoes unleashed by Hurricane Milton marked a turn in Florida’s encounters with twisters.
Blamed for killing at least six people and injuring four others, 26 tornadoes have so far been confirmed amid more than 120 warnings triggered hours before Milton made landfall near Siesta Key Oct. 9 with 120-mph winds.
Three that hit St. Lucie, Palm Beach and Glades counties were ranked severe, with an EF3 rating, with winds reaching between 140 and 155 mph. A closer look at single supercell near Clewiston, that was initially suspected of producing a longtrack tornado that traveled about 70 miles before it dissipated, actually produced four individual twisters.
“It’s just remarkable,” said Michael Lowry, a hurricane specialist with WPLG and former senior scientist with the National Hurricane Center. “These are Midwest-style tornadoes in South Florida.”
The EF-3 tornadoes mark the first time such tornadoes have appeared in South Florida under the new tornado rating scale adopted by the National Weather Service in 2007, NWS Miami Meteorologist-in-Charge Robert Molleda said in an email. Prior to that, three F-3 rated tornadoes were recorded under the previous scale that factored in fewer variables, with the most recent forming in Broward County in 1980, he said.
To fire up such fierce twisters, Milton set the stage for a perfect mix of ingredients.
After churning across the Gulf of Mexico for nearly five days, it pushed ashore a soupy mix of moist Caribbean air, Lowry explained. When that collided with dry inland air out of reach of the hurricane’s protective cloud cover, it destabilized the atmosphere amid daytime heating and increased wind shear to form the twisters.
Some lasted just minutes, like one in Okeechobee County that appeared and vanished in just five minutes. The St. Lucie County tornado lasted 31 agonizing minutes, traveled more than 21 miles and measured as wide as four football fields.
“So it was very similar but different in how the tornadoes come about in the Midwest, where you have this drier air to the north colliding with very rich, soupy air from the south,” Lowry said. “You have to have a very unique setup for that to happen. Not every hurricane is hitting Florida from the west, as this one was, and moving from southwest to northeast. That direction is really important.”
Tornadoes are common in hurricanes, which can trigger the swarms produced by Milton, he said. When Hurricane Ivan made landfall in Alabama and brushed Florida’s Panhandle in 2004, it spawned 118 tornadoes. Frances produced 103 that year when it hit Stuart as a Category 2 hurricane. Hurricane Beulah produced 115 when it hit just south of the Rio Grande in 1967.
“So that's always a hazard associated with hurricanes,” he said.
What’s unusual is to have so many severe tornadoes at once.
“We don't talk about tornadoes so much with hurricanes because they tend to be weak,” he said. “Ninety percent of hurricane spawned tornadoes are EF0 or EF1. And because they are weak, they sort of get mixed up in the overall winds of a hurricane.”
Only about 3% of deaths have been blamed on tornadoes from hurricanes. The majority are due to water, from either storm surge or flooding.
In an update provided late Tuesday, the National Weather Service's Miami office said the first tornadoes appeared several hours before daylight Oct. 9. at the southern tip of Florida.
About 4:30 a.m., the first popped up northwest of Florida City and traveled nearly 3 miles with 87-mph winds before dissipating just over 10 minutes later. Four hours later, a second tornado appeared just north near the Tamiami Trail and the Big Bend and traveled just over nine miles with 80 mph.
About 9:40 a.m., the first of four tornadoes in what were initially suspected of being a single longtrack twister touched down near Alligator Alley at the Miccosukee Tribe's service station and was photographed by a traffic camera. Its intensity is unknown. The tornado traveled about 13.5 miles for 24 minutes before dissipating on the Seminole Tribe's Big Cypress reservation.
Minutes before it vanished, another appeared near I-75 about 9 miles west of Weston. Its intensity is also unknown. It traveled nearly 4.7 miles and lasted nine minutes, according to the weather service.
At 10:42 a.m., a third tornado in the cluster appeared east of Moore Haven with 95 mph winds and trekked nearly 17 miles before dissipating in sugarcane fields.
The fourth twister appeared just before 11:30 a.m. in Ortona, northeast of LaBelle, with 110 mph-winds and traveled nearly 30 miles before falling apart.
Meanwhile, afternoon twisters were about to become more fierce.
About 11:45 a.m., the first formed near the Seminole Tribe's Brighton Reservation. With 110-mph winds, it blasted apart manufactured homes as it traveled just over 6 miles, the weather service reported.
Two hours laters, at 2:15 p.m., a cluster of three tornadoes appeared in Hendry County, with winds between 60 mph and 107 mph, and lasted just under 10 minutes.
As they ended, a massive EF3-rated tornado appeared northeast of Moore Haven and ripped through the Sarasota Colony neighborhood with 140- mph winds. For more than 20 minutes, it traveled nearly 16 miles, destroying homes. An SUV was flipped and manufactured homes lifted off the ground, the weather service reported.
Within minutes, the first of three tornadoes in Palm Beach County appeared. A storm chaser spotted one at 2:49 p.m. west of Lion Country Safari and a second about 4:30 p.m. east of State Road 80. The intensity of the tornadoes was not known, but together they traveled more than 35 miles.
At 4:43 p.m., a powerful EF3 with 140 mph winds popped up west of Wellington. For the next 35 minutes or so, it plowed north, crossing Southern Boulevard into the Acreage and intensifying as it neared Northlake Boulevard before slamming into the Avenir community, where it collapsed part of a roof on a newly constructed Publix about to open, tossed some vehicles at least 100 yards and damaged trees and power lines as it entered Jupiter Farms.
As of Wednesday, four tornadoes had been confirmed in Highlands County, closer to where Milton made landfall, with winds between 80 and 115 mph.
Scientists are still investigating what impact a warming planet will have on tornadoes produced by hurricanes. Some studies have suggested they are likely to become more frequent, and occur at night, when people are less alert. But teasing out the connections is complicated.
Milton will likely give scientists more evidence to examine, Lowry said.
“I can imagine that the severe weather experts looking at tornadoes are going to look into this during the off season to see if there's a connection to climate change or why we had so many strong long-track tornadoes this hurricane season,” he said.
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