America is likely to get more killer supercells spawning tornadoes and hail as the world warms, according to a new study that also warns that deadly storms will head east to strike more frequently in more populous southern states, such as Alabama, Mississippi and Tennessee.
The superstorm that devastated Rolling Fork, Mississippi is one event that cannot be linked to climate change. But he fits this predictable and more dangerous pattern, including more nighttime strikes in a southern region with more people, poverty, and homes at risk than there have been storms in the past century. And the season will start a month earlier than before.
The study in Bulletin of the American Meteorological Society It predicts a 6.6% increase in supercells nationwide and a jump of 25.8% in the area and the time when the strongest supercells will twist and tear above Earth under the future moderate levels of warming scenario by the end of the century. But in certain areas in the south the increase is much higher. This includes the Rolling Fork, in which the study authors project an increase of one supercell per year by 2100.
Supercells are nature’s ultimate storms, called “God’s Finger” and are “the dominant producer of large tornadoes and hail,” said lead author Walker Ashley, professor of meteorology and disaster geography at Northern Illinois University. Tall, anvil-shaped and sky-high, the supercells have expanse Periodic strong update from the wind and can last for hours.
Supercells produced the 2013 Moore, Oklahoma, tornado that killed 51 people, the 2011 Joplin, Missouri tornado outbreak that killed 161 people, and the 2011 supercell outbreak that killed more than 320 people in Alabama, Mississippi, Tennessee, and the Central South.
The study used computer simulations to predict what will happen by the end of the century with different levels of global carbon pollution levels. But Ashley said an even stormier future looks like it’s already here.
Ashley said in an interview three days ago EF-4 Tornado More than 20 people were killed in Mississippi on Friday. “What we see in the long term is really happening now.”
Ashley and others said that although the Mississippi tornado fit the forecast pattern, it was a single weather event, differing from the climate forecast over many years and a large area.
Ashley and study co-author Victor Gensini, another professor of meteorology at Northern Illinois University and a longtime hurricane expert, said they are watching for the potential for another supercell in the mid-South on Friday.
Previous studies have not been able to predict supercells and tornadoes in future climate simulations because they are such small-scale events, especially tornadoes, that global computer models cannot see. Ashley and Jenseni used smaller regional computer models and compensated for their reduced computing power by spending two years running simulations and processing data.
Three scientists not associated with the study said that makes sense. One of them, Penn State University hurricane scientist Paul Markowski, calls it a promising advance because it explicitly simulates storms, compared to previous research that only looked at general environments favorable to supercells.
While the study found an overall increase in the number of supercells, what it found mostly were significant shifts in where and when it strikes — generally, east of Interstate 35, which runs through east-central Texas, Oklahoma and Kansas, and less to the west.
Under moderate warming – a decrease in the world’s temperature based on current emissions – parts of eastern Mississippi and eastern Oklahoma are expected to get three more supercells every two years, with eastern Texas, Arkansas, Louisiana, Alabama, western Tennessee and eastern Georgia getting one more supercell every two years. .
With worse warming – than the world is currently on track for – the study predicts similar but deteriorating supercell changes in eastern Oklahoma, Arkansas and southern Missouri.
Ashley said cities that should see more supercells as warming gets worse include Dallas-Fort Worth, Little Rock, Memphis, Jackson, Tupelo, Birmingham and Nashville.
A moderate warming simulation predicts supercell increases of 61% in March and 46% more in April, while the more severe warming scenario would have increases of 119% in March and 82% more in April. And they’re seeing double-digit percentage declines in June and July.
In the Mid-South, including Rolling Fork, the study predicts that supercell activity peaks two hours later, from 6 to 9 p.m. instead of 4 to 7 p.m., meaning more nocturnal supercells.
“If you want disaster, create a super cell at night where you can’t come out and visually confirm the threat” so people don’t take it seriously, Gensini said.
The eastward shift also puts more people at risk because these areas are more densely populated than traditional tornado alley in Kansas and Oklahoma, Ashley and Jenseni said. The populations at greater risk are also poorer and frequently live in mobile or manufactured homes, which are more dangerous locations in a tornado.
What’s likely happening as the climate warms, Ashley and Jenseni said, is that the U.S. Southwest is getting hotter and drier. Meanwhile, the Gulf of Mexico, which provides the moisture necessary for storms, is getting hotter and the air coming from there is getting juicier and more unstable.
Hot, dry air from places like New Mexico puts a stronger “hood” over where storms usually form when air masses collide in the spring. This cover means that storms can’t boil over as much as on the Great Plains. Pressure builds as the weather front moves east, Gensini and Ashley said, causing giant cells to form later and farther east.
Because February and March are getting warmer than they were before, this will happen earlier in the year, but by July and August the mantle of dry hot air is so strong that supercells have a hard time forming, Ashley and Jenseni said.
Ashley said it was like playing with a pair of dice loaded against you. One of these dice makes the odds worse due to more people getting in the way and the other is filled with more supercells “which also increases the odds of hazards, tornadoes and hail”.
Walker S. Ashley et al., The Future of Supercells in the US, Bulletin of the American Meteorological Society (2022). DOI: 10.1175/BAMS-D-22-0027.1
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