U.S. reacts to spate of tornadoes as weather expert explains their formation

ammered by the deadly tornadoes, with a disaster declaration for the state following a request from its governor. The spate of tornadoes that struck six states included one that hit Kentucky the hardest. Beshear said "the storm event was the longest tornado track on record and the largest in Kentucky history."

The declaration makes federal funding available for storm victims in the western Kentucky counties of Caldwell, Fulton, Graves, Hopkins, Marshall, Muhlenberg, Taylor and Warren, as well as for state and "eligible local governments and certain private nonprofit organizations on a cost-sharing basis for emergency work" there, a White House news release said on Sunday.

The assistance available to residents affected by the storm includes "grants for temporary housing and home repairs" and "low-cost loans to cover uninsured property losses." Biden also ordered federal aid to supplement recovery efforts. He said on Saturday that his administration is "ready to do the same for the governors of the other states" affected by the storm if they request an emergency declaration.

Photo taken on Dec. 11, 2021 shows a tree toppled in tornadoes in Mayfield, Kentucky, the United States. (Photo by Caromirna Sanchez/Xinhua)

UNPRECEDENTED INTENSITY

A combination of the main tornado's enormous path as it tore from Arkansas to Kentucky, its sheer power and the high number of smaller whirlwinds that accompanied it made for an overwhelming force that left devastated communities in its wake. December tornadoes are uncommon but not unheard of, but the explosion of twisters across the states over the weekend might be unprecedented, reported USA Today on Monday.

"Tornadoes do happen at this time of year, but the number in which they happened and the intensity in which they happened Friday night is what is rare," Dan DePodwin, director of forecast operations for weather forecasting services provider AccuWeather, was quoted as saying. "On average, in December, there are roughly two dozen tornadoes (nationwide). We're going to surpass that just on the one night Friday."

A three-year average of 47 tornadoes has been reported in the United States during the month of December, according to the Storm Prediction Center. The multi-state outbreak is shaping up to be unusual, especially in how much farther north than usual it occurred. In addition, the number of fatalities that the outbreak may have caused is exceptionally rare, as the month of December rarely sees tornado fatalities at all.

Photo taken on Dec. 11, 2021 shows houses damaged in tornadoes in Mayfield, Kentucky, the United States. (Photo by Caromirna Sanchez/Xinhua)

FORMATIVE ATMOSPHERE

"The unusual warmth in the north that preceded the outbreak was one of the main ingredients that drove it to occur. It's typically not so warm this time of year for that region, so outbreaks are usually unable to form," reported AccuWeather on Sunday, while quoting DePodwin as saying that "I think the warm December certainly played a role. We haven't had a lot of cold fronts make their way all the way down into the Gulf of Mexico yet."

The Gulf of Mexico being at or above normal this time of year can further aid in the transport of warmer air northward, which is what helped fuel the multi-state outbreak. As the warmer air from the Gulf moved north, a very strong low pressure area was moving out of the Rockies and into the Great Lakes region. This pulled the warm and moist air even farther northward, said AccuWeather.

Four main ingredients needed for severe weather were prevalent to ignite the outbreak, explained DePodwin, adding that "you need moisture, which we had from the Gulf of Mexico. You need instability, rising air. You need colder air aloft, we had that. You need some type of lifting mechanism, a cold front in this case. And then you need some type of turning in the atmosphere or wind shear, as we call it." ■

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