"One of the great things about living in Alabama - and I say this after every major emergency we have - it truly is amazing to see what's happening out there with all the families in this state," Riley said.
At least 50 people were injured, and about 200 homes and 40 businesses were damaged in the Prattville area, according to the National Weather Service. No deaths were reported. Two people who were critically injured were upgraded to serious on Monday, said Todd Stacy, a spokesman for the governor.
At least 11,000 homes and businesses in Prattville lacked power after the storm.
The tornado was part of a system that swept across the Southeast on Sunday, damaging homes elsewhere in Alabama and in parts of Georgia and the Florida Panhandle.
The violent weather continued into early Monday, when a tornado ripped apart a house in Hookerton, N.C., slightly injuring three people.
"It sounded like a train came through my window," said Shannon Edwards, 19, who was trapped under debris for about an hour at her family's home. "My whole bed just flipped up. I didn't know where I was going to end up. I didn't know what was going on."
Scattered damage to buildings and trees was reported elsewhere in North Carolina.
The tornado that struck Prattville tore up a path about a quarter-mile wide and had winds of 140 to 150 mph, said meteorologist Jim Stefkovich at the National Weather Service's Birmingham office.
"God was watching over our city last night," Mayor Jim Byard said, adding that if the storm had hit in the middle of the night as happened in northern Alabama earlier this month, it could have been fatal.
The death toll from those storms, part of a tornado outbreak that ripped across several Southern states Feb. 5 and 6, rose by one to 57 on Monday after a Tennessee man died of his injuries, emergency management officials said.
Repair crews also were at work Monday in western and central Georgia, where the storms destroyed or damaged more than 50 homes Sunday, according to the Georgia Emergency Management Agency. Ten people were injured, two of them critically, the agency said.
While tornadoes were battering the Southeast on Sunday, parts of the Upper Midwest had to deal with ice and snow.
Dozens of schools in central and eastern Iowa were closed or had delayed openings Monday and travel was not recommended on some highways because Sunday's storm dumped as much as 6 inches of snow, accompanied by wind gusting to 50 mph.
According to the weather service, a total of 18.5 inches of snow has fallen so far this month at the Des Moines International Airport, compared with the average 5 inches. So far this season, Iowa has gotten 48 inches compared with the normal 26 inches.
