Unusual number of hurricanes: tornado alarm in the USA

More than 60 people have been killed by hurricanes in the United States this year. What is the reason for the increasing frequency of tornadoes? And is it related to climate change?

“It’s happened again,” the moderator on PBS television welcomed his viewers on Wednesday. A tornado killed at least five people in southeastern Missouri. It was breathtaking, reported a shocked resident, a big mess with fallen trees.

Bad news of this kind has been coming out almost every day for the past few weeks. Over 60 people have been killed by hurricanes this year. By way of comparison, a total of 23 people died from tornadoes last year. The number of hurricanes is also significantly higher than in other years. So far around 400 have moved across the country. The Midwest, i.e. states such as Oklahoma, Kansas and Nebraska, as well as the Southeast with, for example, Mississippi and Alabama are particularly affected.

Warmer Gulf of Mexico increases tornado risk

“The reasons the central US is so prone to tornadoes are — at the lower levels — southerly winds bringing warm, humid air from the Gulf of Mexico, and at the upper levels, winds from the Rocky Mountains and the deserts of the southwestern United States, which bring relatively dry, cold air,” says Harold Brooks, scientist at NOAA, the weather agency of the United States. This combination first leads to thunderstorms, which, in combination with strong winds, can then create hurricanes.

At the moment the Gulf of Mexico is warmer than average – an important explanation for the high level of activity. The fact that so many people died has something to do with the path of the storms. When tornadoes sweep across the sparsely populated Great Plains, they don’t often encounter development. Unlike in the Mississippi Delta, for example, where many people live in rural areas, says Howard Brooks. “Also, there’s a lot more poverty in the Southeast than on the plains. More people live in mobile homes. All of this combined makes tornadoes deadlier in the Southeast than on the plains.”

Accurate warnings are difficult

It is possible to predict when and where tornadoes will form, but not exactly where they will hit the ground and where they will pass. Warnings are therefore only issued at short notice for a larger radius, via warning app, sirens and sometimes also by police vehicles.

But if all of this happens in the evening or at night, it may be too late for people in the countryside – like in Rolling Fork, Mississippi, at the end of March. “My city is gone, but we are resilient and we will come back strong,” said Eldrige Walker, CNN’s mayor. A strong category EF 4 tornado passed through the city after 8 p.m. At over 270 kilometers per hour, it knocked down the water tower and roofs. More than 20 people died.

Whether the high number of tornadoes has something to do with climate change? The experts are cautious. The overly warm water in the Gulf is certainly an important factor. The season could possibly start earlier and last longer in the future. But as ferocious as tornadoes are, compared to global warming itself, they’re a small, localized phenomenon.