Interstate 75 commuters move away from Florida’s west coast ahead of the arrival of Hurricane Milton
Marco Bello / Reuters
Hurricane Milton spawned at least two large tornadoes before making landfall along Florida’s west coast tonight, prompting a tornado watch for much of the southern part of the state.
Such tornadoes are not rare – they are seen more than once 80 percent of hurricanes It made landfall on the Gulf Coast, but it’s unusual to see them so clear before a hurricane, he says William Gallus at Iowa State University. “There’s already been a surprisingly large number and they look like Great Plains tornadoes,” he says. “They are wide.”
Hurricanes require two main components to form tornadoes, which increase the destructive potential of a storm. The first is the instability created by the heat and humidity in the atmosphere. Second, differences in wind speed and direction at different heights, known as wind shear.
Hurricanes moving over water usually have relatively low wind shear because there is not much friction between the storm and the sea surface. “It’s like this giant spinning cylinder, so the winds aren’t much different than they are up on the ground,” says Gallus.
This changes as the storm makes landfall, and friction with the ground slows the winds at lower altitudes, which also pulls them toward the center of the storm. When the air is sufficiently warm and humid, these strong winds can produce tornadoes.
In this case, wind bands ahead of Milton’s main body have reached the coast, creating wind shear and spawning tornadoes, Gallus says.
Along with other hurricane hazards, such as storm surge and heavy rainfall, tornadoes can cause extensive destruction, visible in the pattern of debris their path sometimes leaves behind. According to one appreciateAbout 3 percent of tropical storm-related deaths in the U.S. were caused by tornadoes; one earlier appreciate He put the number at 10 percent of the dead.
Such tornadoes may also become more frequent as climate change raises temperatures in the lower atmosphere, adding to the unstable conditions in which tornadoes form. In the end to analyzeGallus and his colleagues simulated how four different hurricanes – Ivan, Katrina, Rita and Harvey – might behave in a very high emissions scenario with the warming expected by mid-century. The number of tornadoes spawned by each storm in the simulation increased significantly, from a 56% increase for Harvey to a 299% increase for Katrina.
“Even if you only get half that, the increase in the number of tornadoes would be very significant,” says Gallus.
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