About 1,200 tornadoes hit the United States each year. The disease is prevalent in the United States, far more than anywhere else in the world, and because its geography provides perfect conditions, especially in the spring and summer. Westerly winds from the Pacific drop moisture as they cross the Rocky Mountains and become higher, drier and cooler as they move eastward. Similar winds may also blow from Canada. Meanwhile, low, warm, moist air flows north from the Gulf of Mexico. The flat terrain along these paths allows the winds to travel relatively uninterrupted at contrasting altitudes before hitting each other. The angle at which a tornado hits tends to create air instability and wind shear, two major factors driving tornado formation. Similar air masses collide in other places, such as Uruguay and Bangladesh, but the forces are much stronger than in the United States, and Canada ranks second in the world with 100 twisters per year.
Tornadoes land in many places in the eastern half of the country, but the most frequent tornadoes from the 1950s to the 1990s occurred in an oval-shaped region centered in northeast Texas and south-central Oklahoma. It was an array. More recently, its focus has moved 400 to 500 miles east. Over the past decade or so, tornadoes have swept through eastern Missouri and Arkansas, western Tennessee and Kentucky, northern Mississippi and northern Alabama, creating new areas of intense storm intensity.
Tornado activity in early 2023 exemplifies this trend. On March 24, a violent twister with winds of 170 mph hit Rolling Fork, Michigan, killing at least 26 people. A week later, a storm hit New Tornado Alley, killing more than 30 people, and on April 4, another group damaged more than 80 structures in Bollinger County, Missouri. These events occurred just before peak season in April and May.
Data collected over the past two years show that in addition to single storms, large tornado outbreaks (multiple tornadoes generated by a single weather system) have moved more definitively eastward. shown. The herds congregate in a geographically smaller area than Old Tornado Alley. And epidemics can become more intense and more frequent. “The United States seems to have fewer single tornado days and more multiple tornado days,” said Naresh Devineni, an associate professor at the City University of New York who co-led the 2021 geographic analysis. Occurrence of a large tornado.
Why is this change happening now? Tornadoes are most often caused by supercells, strong thunderstorms with rotating updrafts. Supercells tend to form when warm, moist lower air interacts with cooler, drier upper air, and climate change is producing warmer, wetter air. Tornadoes are also more likely to form if the local atmosphere is unstable. “Warming will increase instability,” says Zuohao Cao, a tornado expert at the Canadian Center for Environment and Climate Change and co-leader of a recent study on where storms land. Climate change is also warming the Gulf of Mexico, which could bring massive amounts of water vapor into the southeastern United States.
Studies suggest that the so-called dry line is also moving eastward. This imaginary line extends north from the U.S.-Mexico border to Canada and separates the humid eastern U.S. from the dry western U.S. Strong wheat prevails). For centuries it has been located roughly along the meridian, but since the late 1800s it has moved eastward about 140 miles. Ernest Age, professor emeritus of atmospheric sciences at Purdue University, said in a 2022 interview that dry lines “could be convective boundaries, where warm air rises and cold air sinks, potentially triggering storms.” There is,” he said.
Climate change could also extend the typical tornado season.A mild winter means that unstable air masses that could form supercells could become more likely in March or sooner in the southeastern United States.
Tornado Alley heading east is more than just a meteorological curiosity. This change is serious. Tornado shelters are common in Texas and Oklahoma, but less common elsewhere. The Southeast is densely populated and trailers that cannot withstand storms are much more common. Tornadoes in the southeast are also more likely to occur at night than in areas further west, in part because the winds bring in plenty of moisture from the bay after dark. The study found he was 2.5 times more likely to cause fatalities in tornadoes that occur at night.
Local and state governments in new hotspots should improve local shelters and warning systems, strengthen building codes, better equip emergency responders, and what to do when a tornado is approaching. You may want to educate your residents about what not to do. .
