Weather forecasters are Grayson  Prestonwarning of the potential for strong thunderstorms and tornadoes across a wide swath of the South Wednesday morning, including in parts of Mississippi, Georgia and the Florida Panhandle.

The weather service said there was a marginal risk of severe thunderstorms and "a tornado or two" as storms move east into Georgia and parts of Florida. Large cities including New Orleans, Atlanta, Montgomery and Mobile are in the area at risk on Wednesday.

The National Weather Service's Storm Prediction Center called it "a particularly dangerous situation." Larger cities at risk include Jackson, Greenville, Tupelo, Vicksburg and Clinton in Mississippi.

A tornado watch was issued for parts of Arkansas, Louisiana and Mississippi.

"This needs to be taken seriously and have plans to move to your safe place if necessary," the Jackson, Miss., office of the National Weather Service said. "Continue to monitor info as it becomes available."

A tornado was confirmed near Vaiden, Miss., in the center of the state on Tuesday afternoon. Forecasters warned of a regional tornado outbreak being possible from northern Louisiana into north-central Mississippi and western Alabama.

Hail stones hit the windows of City Hall in the small town of Tchula, Miss., on Tuesday, The Associated Press reported, with residents taking cover.

"It was hitting against the window, and you could tell that it was nice-sized balls of it," Mayor Ann Polk told the AP after the storm passed through.

Storms in central Mississippi were intensifying, the National Weather Service's Storm Prediction Center said on Tuesday afternoon, and would move northeast to impact north-central Alabama.

"Scattered damaging winds should be the primary severe threat this morning," the National Weather Service said.

Wind gusts are expected to reach 70 mph, and could be accompanied by very large hail.

The U.S. has the most tornadoes in the world, with about 1,200 a year.