A powerful storm system is forecast to unleash heavy rain, strong winds and thunderstorms capable of spinning up tornadoes this week across much of the south-central United States, an area that was battered just last week by deadly storms.

The low-pressure system invigorated by moisture from the Gulf of Mexico began a slow, multi-day journey from Texas to the Great Lakes region on Monday. As it headed east, severe weather was expected to hit the Gulf Coast, the mid-Atlantic and the Midwest regions, the National Weather Service said. The threatening forecast led organizers of the Texas Eclipse Festival to end the celebration early Monday and Texas Gov. Greg Abbott to activate emergency response resources.

More than 30 million Americans from eastern Texas to Mississippi were at risk of severe weather Tuesday, when heavy rain, wind, "large hail" and several tornadoes were expected to lash the region, the storm prediction center said. The highest risk of flooding was in the Texas Panhandle Tuesday night and the mid-South on Wednesday, the weather service said.

More than 54,000 homes and businesses were without power in eastern Texas and western Louisiana as of Tuesday morning, according to a database maintained by USA TODAY. The storm also disrupted air travel. More than 31 flights out of Dallas Fort Worth International Airport were canceled and about 120 were delayed, according to FlightAware, a flight tracking website.

On Wednesday, the risk of severe weather will extend to central Georgia and the Florida Panhandle as well as northern Arkansas and parts of Tennessee. The threat of tornadoes is expected to largely concentrate on the Gulf Coast on Wednesday before shifting to the Carolinas and mid-Atlantic region on Thursday, according to AccuWeather.

Abbott mobilized several state entities on Sunday, including the National Guard, the Department of Transportation and the Texas A&M Forest Service to prepare for possible flood, tornado and storm damage.

“Texas is ready to respond with all available resources needed to assist local communities as severe weather, including severe thunderstorms and large hail, begins to impact the state,” Abbott said in a statement, urging people who traveled for Monday's solar eclipse to "remain weather-aware, and monitor road conditions to keep themselves and their loved ones safe.”

Last week, much of the eastern United States was battered by a major storm system that killed at least four people as it unleashed heavy rain, wind, snow, damaging hail and tornadoes from Georgia and Alabama to Ohio and Illinois.