More than 100 million people in east-central and mid-southern U.S. states are at risk of severe weather with large hail, damaging winds, and strong tornadoes expected.
Cities like Indianapolis, St. Louis, Nashville, and Little Rock are under an enhanced risk level for severe storms.
Two waves of thunderstorms are expected, starting early Sunday morning in the at-risk areas.
The severe weather is caused by a strong low pressure system moving across the U.S., bringing warm, moist air from the Gulf.
The severe weather threat will move eastwards, affecting the south, Mid-Atlantic, and northeast U.S.
The Storm Prediction Center uses a five-level risk system to forecast severe weather, ranging from marginal to high risk categories.
Weather watches are issued in advance of impending weather, while warnings indicate that particular weather hazards are expected to occur soon.
Safety measures during severe storms include seeking shelter in basements, interior rooms, or designated safe spaces away from windows.
Drivers should find the closest building to shelter in during severe weather, avoiding taking shelter under overpasses.
Residents of mobile homes should seek shelter in sturdier structures during severe weather events.