Skip to Content

News

Home>Weather News>Why has Hurricane Milton spawned tornadoes?

Search Icon

Why has Hurricane Milton spawned tornadoes?

Anthony Sharwood

Hurricanes and tornadoes are two totally different types of weather phenomena involving swirling destructive winds – hurricanes on a macro scale, tornadoes on a micro scale – so why have the two occurred in unison as Hurricane Milton lashes Florida?

The answer is that under the right conditions, hurricanes can produce exactly the type of extreme weather conditions which are conducive to tornado formation.

  • Hurricanes (which Australians call "cyclones" and are called "typhoons" in most of Asia) are large rotating low pressure systems formed over tropical or subtropical waters with maximum sustained wind speeds approaching or greatly exceeding 100 km/h.
  • Hurricanes only form at sea, but as we know, their winds, rainfall, and storm surges can be devastating as they cross land. Even when a hurricane remains at sea, the storm surge from its winds can be devastating to coastal communities and can inundate low-lying land many kilometres inland.
  • Tornadoes are violently rotating columns of air that reach the ground, usually attached to the base of a thunderstorm from which they are spawned. While often centred over a very small area no bigger than a football field, their winds can come close to 500 km/h – much more powerful than the strongest hurricane or tropical cyclone.
  • Tornadoes, unlike hurricanes, can develop and dissipate extremely quickly. Also unlike hurricanes, they often form above land, and frequently form in temperate zones well beyond the tropics. They are particularly common in so-called “Tornado Alley” in America’s midwest.

So hurricanes and tornadoes are two distinct types of dangerous weather, but as mentioned, they can also occur together, as we have seen with Hurricane Milton over the past 24 hours.

How?

Hurricanes contain many key ingredients for tornado formation – including plenty of heat, humidity and lightning.

As hurricanes approach the coast, the friction with the land helps create the final key ingredient necessary for tornado formation: high wind shear (difference in wind speed).

St Lucie County, about two hours north of Miami on Florida’s Atlantic Coast, was one of the areas devastated by tornadoes before Milton made landfall, with at least two confirmed deaths.

"There were cars lifted and flipped upside down, moved hundreds of yards," County Sheriff Keith Pearson said. "I can tell you that there was nothing left to some of these places but foundations."

Pearson estimated 100 residences were destroyed in the county after roughly 17 tornadoes touched down.

Here in Australia, we rarely if ever hear of tornadoes being associated with tropical cyclones, although that doesn't mean it doesn't happen

Weatherzone meteorologist Joel Pippard says that the isolation of much of northern Australia means that tornadoes might not be reported during tropical cyclone events. He also says that it's difficult to identify tornado damage when everything is flattened after a tropical cyclone.

In heavily populated Florida, where so much footage has been taken of tornadoes in the past hours – and where in some cases the tornadoes touched down before Hurricane Milton made landfall – it has been horrifyingly clear to locals they are facing the prospect of two distinct disasters in one.

Meanwhile Hurricane Milton has just been downgraded to a Category One system late on Monday afternoon (AEDT) as it tracks northeast over the city of Orlando, which is part of Florida’s third-largest urban area.

Note to media: You are welcome to republish text from the above news article as direct quotes from Weatherzone. When doing so, please reference www.weatherzone.com.au in the credit.