The system -- which slowly rolled across the United States all week -- was expected to produce powerful thunderstorms to the Carolinas and Virginia Friday before reaching the Atlantic Ocean, AccuWeather.com reported.
CNN reported the storm claimed three lives in incidents in Missouri, Mississippi and Nebraska.
A woman froze to death after her car broke down near Berea, Neb., when a blizzard struck Monday, state police said.
An employee for Ameren Missouri was electrocuted Thursday while trying to restore power after storms, the company said.
A person died in Kemper County, Miss., Thursday, after strong winds ripped through a steel building along a highway, the National Weather Service reported.
The system brought freezing rain, sleet and snow to the Midwest and Plains states, rains to the Ohio and Mississippi valleys and tornadoes in the Deep South.
A tornado snapped large limbs and caused power outages around Slidell on Louisiana's gulf coast, officials said.
Tornado watches were in effect through Friday morning in parts of Georgia, North Carolina, South Carolina, Alabama and Florida.
In Missouri, Gov. Jay Nixon declared a state of emergency after storms walloped the St. Louis area and other parts of the state Wednesday.
Also hard hit was Arkansas, where Gov. Mike Beebe declared 15 counties state disaster areas.
AccuWeather.com said severe thunderstorms were forecast Friday for the eastern Carolinas and southeastern Virginia. Cities most at risk included Norfolk, Va., Greenville, N.C., and Virginia Beach, Va.
In Minnesota, the entire city of Worthington was without power Thursday because ice snapped miles of power lines, KSTP-TV, St. Paul, reported.
"No heat, no lights, if they don't have any generators or anything like that it can get cold," Great River Energy Foreman Jon Borchert said.
The city is relying solely on city generators for heat.
"We've got 14 mega watts of power -- and that's all we've got," City Administrator Craig Clark said.
"They're rotating through the town. You get 45 minutes of power on, 45 minutes off," homeowner Linda Griffith told KSTP.
The storm also caused more than 100 delays and cancellations at Minneapolis-St. Paul International Airport Thursday, facility officials said.