December tornadoes rising as ‘Tornado Alley’ shifts east

FFew expect a tornado in December, let alone strong enough to topple the 11-inch-thick concrete walls of a massive, new Amazon warehouse.

But the EF3 tornado that devastated the facility near Edwardsville last month – one of several twisters that caused widespread damage and more than 90 deaths in six states – could be a sign of things to come.

While most people associate intense tornado outbreaks with spring, weather experts say both the timing and location can change.

Two decades ago, December’s tornadoes — if they came — plowed through fields and homes from east Texas to northern Florida, according to data from the National Oceanic and Atmospheric Administration, or NOAA. During that time, fewer storms occurred overall, and even fewer struck the country’s traditional “tornado alley”—Kansas, Nebraska, Oklahoma, and Texas. Mississippi, Alabama, Arkansas, Tennessee, Missouri, Illinois and Kentucky have recently tended to touch on unseasonable twins.

Scientists and those studying the phenomenon agree that the tornado’s outbreak is moving east.

“Research has identified evidence of ‘Dixie Alley’, which represents an eastward extension of the traditional ‘Tornado Alley’ in the central Great Plains,” wrote Harold Brooks in a 2018 study on tornado spatial trends. Brooks studied tornadoes at NOAA’s National Severe Storms Laboratory, and said St. Louis has the most notable tornado history of any location in the country.

In general, tornadoes are not happening more often – except in December. Professors and experts give many reasons.

Tornadoes require two main ingredients: warm air, and rapidly changing winds at different levels of the atmosphere, known as wind shear. William Gallus, a professor of meteorology at Iowa State University in Ames, Iowa, said that recent bursts in December tornadoes often have wind shear in geographic areas, but not the warm air that causes atmospheric instability. That is when a parcel of air is heated to the same height as the surrounding air, causing the parcel to rise.

He and his colleagues were puzzled by the dew points produced in Memphis and Kentucky in recent tornado-generating systems. that passed via Iowa on December 15 Gallus said the state broke the record for one-day tornadoes. And that system produced tornadoes in parts of the country that previously had no tornadoes in December.

Some, like Gallus, see a natural link between climate change and increased extreme weather. A warmer planet means an often warmer Gulf of Mexico, he said. Disturbances in the jet stream can result and produce tornadoes – especially in December.

Still others think that varying weather patterns, such as La Nia, which causes wet Midwestern conditions to meet warm southeastern conditions, are the cause. John Allen, a professor of meteorology at Central Michigan University in Mount Pleasant, Michigan, said La Nia can predict severe winter weather, and more frequent. The US is experiencing La Nia weather patterns this winter.

NOAA, the most recent full decade of data available from 2010 to 2019, shows that the December 221 tornadoes were rated on an enhanced Fujita scale of 1 or higher, compared to 143 from 2000 to 2009 and just 78 during 1990 Happened in America. Most of December’s tornadoes were rated at EF2 or lower, meaning weak storms, but the percentage of strong or violent tornadoes increased from 4% to 10% between the past two decades.

And, in the midwestern-southeast states, except Kansas, Oklahoma and Texas — also known as “Tornado Alley” — December’s tornadoes increased to 189, a 78% increase from 106.

NOAA tornado data has limits, said Jan Hauser, a professor of meteorology at The Ohio University in Athens, Ohio. Houser said the first two decades were recorded retrospectively using newspaper archives and other reports. There are now more people to see and report tornadoes, and more ways for them to report more easily.

In 2007, NOAA changed the rating system for tornadoes, moving from measuring wind speed and damage only after hurricanes to measuring their strength to measure damage. Brooks said the change caused discrepancies in the storm’s strength ratings across the data.

In their paper, Brooks and his co-authors note that the geographic trend may be the result of techniques to smooth reports over time and space.

Still, the number of December tornadoes continues to rise.

In December of this year, twice as strong tornadoes hit the Midwest. On December 10 the first offensive system affected Missouri, Illinois and Kentucky and killed eight people. Strong winds blew the foundations of homes and an EF3 tornado collapsed at an Amazon warehouse near Edwardsville, killing and injuring workers trapped beneath concrete walls.

Meanwhile, a twister from the same system Made 200 Miles Through Kentucky, and potentially broke a 100-year-old record for time on land. The town of Mayfield, with a population of about 10,000 people, was devastated, with downed trees and power lines stretching across the landscape. Windows and roofs were blown off the buildings that were still standing. More than 70 people were pronounced dead, and officials are still working on their recovery.

Five days later, a second storm caused the system Hurricane-force winds north of southeastern Minnesota And killed a man there when a 40-foot tree fell on him outside his house. Another person died when a semitrailer was blown over his side in Iowa; Three others died in Kansas, where high dust and low visibility caused vehicle accidents.

Gallus said a total of 90 tornadoes have arrived from all states.

On New Year’s Eve in 2010, an EF3 struck the St. Louis area, leveling homes, toppling at least one business and utility poles in Sunset Hills. The storm continued and pushed the tornado to touch down in northern St. Louis before moving into southern Illinois.

“The weather was terrible, like it is now – hot – and not normal for December,” said Pat Fribis, who is now the mayor and then-alderman of Sunset Hills. “We were just shocked.” Fribis remembers looking at a house whose entire facade had been removed.

“It was like you were looking at a dollhouse,” she said. No one was hurt in the South St. Louis County community, but Fribis described the damage as devastating.

Political issues stemming from the tornado caused Ann McMun to run for office. She is now an alderman representing the 1st Ward in Sunset Hills and remembers New Year’s Eve like it was yesterday. She was alone in her three-bedroom house when a tree fell from the house and the storm leveled most of her street.

He remembers hearing two tornado sirens at first. He ignored them until the third one was gone, when he peeped out, and saw a green sky and rain side by side. He called his mother, who was at a shanks in Crestwood. Minutes later, she was standing in the basement, still on the phone, when she got hit.

“There was a moment when I was talking to my mom, and I couldn’t hold my breath,” McMun said. “I told my mom, ‘I guess it must be right on me.'”

In 2000, a tornado that struck Alabama near Tuscaloosa in early December killed 11 people and destroyed an entire shopping center before moving to flat homes. The storm overturned vehicles and injured 144.

“Ironically, the tornado dissipated as soon as it moved into an open, populated area,” National Weather Service reported,

More research is needed to understand how, and why, the December tornadoes accompany. But collecting data on one of the fastest-moving and random weather events isn’t exactly easy, Gallus explained.

“I have to be a trillionaire, and cover the whole country with weather tools,” Gallus said. Still, they’ll likely be blown up before much meaningful data can be collected.

Meteorologists can only recommend a few things that potentially get in the way of unseasonal twisters: Prepare, have a plan, and have a safe place to go.

To prepare, residents can build substantial shelters. And for those who have bad knees, it is not necessary to have a basement of the place.

Brooks has an above-ground shelter in his residence, with concrete walls reinforced with steel bars every six inches, and a steel door.

Companies like Amazon may redesign their warehouses to create enough safe space for all employees.

“It’s hard to reinforce a building of that size, but you can build smaller shelters for your entire population,” Brooks said. “You spend an essentially small amount of money making part of the building really safe.”

In 2021, ahead of year-end data collection and cleanup, Gallus said December’s tornado count had already reached 160, according to weather station reports across the country.

“It’s probably safe to say that growth will continue into the 2020 to 2029,” Gallus said.