(CNN)As frigid, arctic air engulfs the Upper Midwest and Northeast, some Gulf Coast states are at risk for more tornadoes.
About 10 million people are under wind chill advisories in parts of North Dakota, Minnesota and Wisconsin, where wind chills are expected to plummet to -25 to -40 degrees Monday.
Parts of New York, Vermont and Massachusetts are also under wind chill advisories through Tuesday, with wind chills expected to plunge to about 35 degrees below zero.
Such "dangerously cold wind chills could cause frostbite on exposed skin in as little as 10 minutes," the National Weather Service said.
This deep freeze will extend across the Northeast by Monday and Tuesday. On Tuesday morning, interior parts of the Northeast and New England could face sub-zero temperatures.
The brutally cold air and fierce winds will lead to heavy lake effect snow downwind of Lake Superior and Lake Ontario.
And by Tuesday morning, parts of Michigan's Upper Peninsula and the Tug Hill Plateau of New York could have more than a foot of snow on the ground, the National Weather Service's Weather Prediction Center said.
A tornado touches down in rural Alabama
More than 10 million people from eastern Texas to the Florida panhandle are under weather advisories Sunday as severe storms roll across the Gulf Coast.
At least one tornado was confirmed late Sunday afternoon in southern Alabama, near McKenzie, the NWS said. There were not immediate reports about damage or injuries.
A tornado watch was in effect for parts of Mississippi and Alabama through 6 p.m. (7 p.m. ET) Sunday.
"Damaging gusts, a couple of tornadoes, and isolated large hail will be possible today across parts of Louisiana, Mississippi, and Alabama," the National Weather Service's Storm Prediction Center said Sunday.
As of Sunday afternoon, there was a level 2 out of 5 risk for severe storms in Mississippi and Alabama.
Flooding could also be an issue for parts of the Gulf Coast, with some areas expected to get 2 to 3 inches of rain.
'Extremely dangerous travel conditions'
In the Northeast, freezing rain and sleet have blanketed parts of Pennsylvania and New York. Other areas in the region are getting walloped with snow.
"Significant icing" was forecast for parts of central Pennsylvania, said the National Weather Service office in State College, Pennsylvania.
It said a quarter to a half inch of ice is expected to accumulate Sunday.
"Extremely dangerous travel conditions. Untreated surfaces will be very slippery. Isolated power outages are possible," the NWS office said.
Residents are urged to avoid driving unless absolutely necessary.
"If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency," the NWS office in State College said.
Wide swaths of New England were expected to get anywhere between a glaze to a quarter inch of ice Sunday. But most of the ice accumulations are forecast to stay west of the major metro areas.