The National Weather Service said the powerful storm had mostly left the south by late Friday and was moving to the northeast, where it was forecast to cause heavy snow and sleet from southeastern Michigan east to New York state. Parts of central New York and southern New England may see over a foot (30cm) of snow by this afternoon.

Kentucky governor Andy Beshear said at least two tornadoes sparked by the storm system ripped through the western part of his state on Friday. The governor said on social media that at least three people were killed in the severe weather, though he did not provide any more details. A fourth person was killed by the storm Kentucky, a woman who died when a tree fell on the car she was in, the Fayette County coroner’s office said.

Aside from the tornadoes, Beshear said thunderstorms in Kentucky were generating winds of 80mph (128.75kmph), which are “strong enough to blow tractor trailers off the road.”

Alabama governor Kay Ivey said on social media that three people were killed in the storm in her state, though she provided no details.

In Arkansas, a man died when he was swept into a swollen river by flood waters after driving on a flooded street, according to the Scott County sheriff’s department.

In Mississippi, governor Tate Reeves said on social media on Friday that overnight storms producing high winds had resulted in one person’s death, though he gave no more details.

More than 1.4 million homes and businesses were without power in states impacted by the storm, according to data from PowerOutage.us.

Violent storms are frequent in the southern US in winter months, as warm, moist air comes up from the Gulf of Mexico and collides with colder air moving down from the north, meteorologists say.