Tornado Threat Rises Across South as Thunderstorms Sweep US

Tornadoes, hail and severe thunderstorms are likely to rip across the U.S. South on Thursday, with more than 1.7 million people facing the greatest risks, the U.S. Storm Prediction Center said.

A large area of unsettled weather that stretches across the Mississippi River valley, the South and up into the Midwest is the culprit, said Marc Chenard, a senior branch forecaster at the U.S. Weather Prediction Center. Northern Alabama and Mississippi face the greatest threat.

“Today is the big day and tomorrow it is winding down,” Chenard said. “The combination of strong winds and high instability is not a good combination overall and that is where we have the high risk.”

Severe thunderstorms, which include storms spawning tornadoes, hail and straight-line winds, were the second-costliest extreme weather events in the U.S., causing $330 billion in insured losses since 1990, according to insurer Aon Plc. The only perils causing more damage were hurricanes and tropical storms.

While the tornado threat is mainly confined to the South, there will be high winds sweeping through the Midwest from southern Illinois to western Pennsylvania, the National Weather Service said.

Flood watches have also been posted across much of eastern Tennessee, as well as parts of Alabama, North Carolina and Georgia as heavy rain could fall throughout the region.