(Reuters) – A dangerous weather system packing severe thunderstorms was expected to roll through the U.S. Southeast and parts of the Midwest on Wednesday, bringing with it the threat of tornadoes, forecasters said.

The region faced the threat of supercells developing throughout the day as very large hail and damaging straight-line wind appear to be likely, the National Weather Service said in an advisory.

At about 5:30 a.m. local time, a thunderstorm was moving northeast of Anniston, Alabama, at 55 miles (89 km) per hour, bringing with it hail the size of golf balls and 60 mile (98 km) per hour wind gusts, the Weather Service reported.

“For your protection move to an interior room on the lowest floor of a building,” the National Weather Service warned in an advisory.

Kentucky, Tennessee, Alabama, Georgia and South Carolina faced a heightened chance of tornadoes and potential flash flooding during the day.

The 5.7 million people who live in the Atlanta metro area should expect as much as 2-1/2 inches (6 cm) of rain throughout the day and into the evening, the service said.

Dozens of school districts in Alabama and Georgia canceled classes while Alabama Governor Robert Bentley issued a state of emergency ahead of the storm front.

“Alabama is no stranger to the impact severe weather can have on communities and the devastation that can occur when the weather takes a turn for the worse,” Bentley said in a statement.

The severe weather comes days after a powerful storm system in the southeastern U.S. killed four people, including a woman who was swept away by flood waters while she called 911.

(Reporting by Brendan O’Brien; Editing by Chizu Nomiyama)