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What is the "alley of tornadoes" and why its movement towards populated areas of the East worries experts


Dozens of people have been killed in the US this year by powerful tornadoes, as the busiest season has just begun. The intensity of these storms is becoming "more severe", an expert warns, and the impact zones appear to be changing for the worse.

A series of devastating tornadoes in the southern and Midwestern United States have killed more than 60 people in recent weeks and left a trail of destruction in their wake: flattened homes, snapped trees, upturned cars, roofless buildings and entire neighborhoods wiped off the map.

The number of people killed by tornadoes so far in 2023 in the country is already almost triple the total number of deaths from the same cause last year: 23.

Historically, tornadoes have primarily affected a region of the Great Plains in the center of the country known as Tornado



which stretches from North Texas to Oklahoma. Kansas, Nebraska, and South Dakota


Meanwhile, their threat shifts from the Southeast in the coldest months of the year, to the Central and Southern Plains in May and June, and to the Northern Plains and Midwest in early summer, according to the Weather Service. National.

[Tornadoes and storms leave destruction and dozens of deaths in the South and Midwest of the country]

But various studies and experts have found that this 'tornado alley' is moving slowly to the East, where there are more populated areas, and suggest that climate change could be one of the causes of this worrying variation, as well as the increase in This type of storm is expected during this century, although more studies are needed to determine a certain cause.

A destroyed home after a tornado struck in Little Rock, Arkansas, on Friday, March 31, 2023. Andrew DeMillo / AP

A scientific article published in the journal Nature in 2018 details that, in recent decades, there has been "a strong downward trend" of tornado reports in parts of the Great Plains, "at the same time as a strong increasing trend " in the areas surrounding the Mississippi River valley,

in states further east, such as Tennessee, Mississippi, Alabama or Illinois.

In Texas, the slight decrease in tornadoes has occurred mainly in the months of March, April and May, while in the plains of Oklahoma, Kansas and Nebraska, it is registered in June, July and August.

[“We got the worst luck”: why the US is the world leader in climate catastrophes]

This year in particular, tornadoes have impacted highly populated areas, especially in southern states like Mississippi and Alabama, where a high percentage of people live in mobile homes, which are more vulnerable, Harold Brooks, a researcher for the Washington Post, told the Washington Post. National Severe Storms Laboratory and one of the authors of the Nature paper.

As Brooks told the newspaper, a person is "between 15 and 20 times more likely to die in a mobile home" compared to a more solid and resistant housing.

In just four months of 2023, almost as many people have been killed by tornadoes as in an average year

April 5, 202302:28

According to Brooks' study, the Mid-South—covering parts of Tennessee, Mississippi, Missouri, Kentucky, Arkansas, and Alabama—has the greatest potential to experience an increase in tornado-caused disasters by the end of the century.

As Brooks explained to CBS News, the change in trends "appears to be an environmental change."

"That means the frequency of tornado-friendly environments has increased over the last 40 to 50 years in the Mid-South region, and has decreased somewhat in South and West Texas."

[Another round of tornadoes is expected in parts of the Midwest, Plains and South]

When asked about the underlying reason, the specialist replied: "It is very tempting to say that it is the result of climate change."

But he clarified that there is not enough proof of this.

"It's probably the result of large-scale changes in conditions. But we don't have as complete a link as we do with other things," he told CBS News.

President Joe Biden (foreground) speaks to residents of Rolling Fork, Mississippi, during his visit Friday, March 31, shortly after a severe tornado struck.Carolyn Kaster / AP

Walter Ashley, an atmospheric scientist at Northern Illinois University, published a study that projects the average number of supercells, large spinning storms that cause the strongest tornadoes, to increase this century.

Ashley explained to the British newspaper The Guardian that there are four key factors involved in the formation of tornadoes.

Two of them are the moisture in the atmosphere and the instability of it, that is, the difference between hot and cold air, which Ashley calls the "gasoline needed for a storm."

According to the expert, both factors are worsening due to global warming.

[Up to 50 tornadoes ripped across the country, leaving at least 30 dead and towns and cities destroyed]

But, according to the report, it is not clear how global warming would affect the other two factors at play: the change in wind direction and speed and the mechanisms that lift particles into the air before they become storms.

"Scientists are working very hard on these questions and we would all like simple answers, but these are difficult questions to answer. I am opposed to linking any single event to climate change," Ashley said.

What is known is that tornado formation is related to the potential for thunderstorm formation.

And a key factor in the formation of these storms is the amount of energy available in the atmosphere for warm, rising air, which is essential in the formation of thunderstorms.

The Wynne High School building, in Wynne, Arkansas, was also destroyed by the tornadoes. Adrian Sainz / AP

A 2022 study from the Climate Central group found that days with a higher level of CAPE—greater potential for thunderstorms—have become more frequent in the East of the country and less frequent in the West.

Walter Ashley, who was not involved in this study, revealed to The Guardian newspaper that human intervention could be affecting the severity of the storms generated by tornadoes.

"We are fundamentally changing the ingredients that make up a tornado, we are rolling the dice towards more severe storms. We are increasing the odds that we will have more severe tornadoes throughout the 21st century, we are seeing that change already happening. The dangers of these storms will probably be bigger as well," he said.

[Up to 50 tornadoes ripped across the country, leaving at least 30 dead and towns and cities destroyed]

"There has been explosive growth in the South in recent years and that unfortunately

means that we are increasing both the number of tornadoes in this area and the number of people exposed to them

," the expert said.

For Ashley, as the area where tornadoes are generated expands to more populated regions, the United States should look at strengthening construction standards to make houses and buildings more resistant to the impact of storms and tornadoes, because these "are not going to go".

Source: telemundo

All news articles on 2023-04-09

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