More than 65 million people in parts of the country’s central and eastern thirds were under winter weather alerts Saturday afternoon, the National Weather Service said.
The storm will swing Saturday night and Sunday to the Southeast with rain, freezing rain and snow before heading to the Northeast Sunday into Monday.
And it’s the freezing rain and ice in parts of the Southeast and Mid-Atlantic that may cause the biggest trouble by Sunday.
“This is by far going to be the biggest issue we encounter over the next 48 hours — ice, and a lot of it,” CNN meteorologist Allison Chinchar said Saturday morning.
Parts of north Georgia and Virginia could get up to a half-inch of ice, and parts of North and South Carolina could see three-quarters of an inch of ice or more, forecasters said.
High winds, coupled with “the weight of that ice on trees and power lines, (are) likely to cause widespread power outages,” Chinchar said.
The governors of Georgia, North Carolina, South Carolina and Virginia declared emergencies, allowing resources to be positioned ahead of the storm’s arrival.
Snow also is expected to impact a number of southern cities by Sunday, making for dangerous travel in places like Memphis, Nashville, Atlanta and Charlotte.
More than a foot of snow could fall Sunday into Monday from the southern Appalachians into the interior Northeast.
Heavy snow — including between 8-14 inches in some areas — fell Friday into Saturday morning in parts of the Dakotas, Minnesota and Iowa.
From there, the system dove into Missouri, Arkansas and Kansas, where it was delivering rain and snow Saturday. Heavy bands of snowfall are expected in the Mid-South and Tennessee Valley throughout the day.
Localized areas of Tennessee could see snow exceeding 6 inches Saturday into Sunday.
Southeast may get a mix of everything
For much of the Southeast, the system will begin in the form of rain on Saturday.
As the temperatures rapidly drop behind a strong cold front, rain will change into freezing rain, sleet and eventually snow for many locations across the Southern Appalachians by Saturday evening.
Georgia Gov. Brian Kemp ordered the state Department of Defense to prepare 1,000 National Guard troops to assist in the response to the storm.
In South Carolina, Gov. Henry McMaster urged residents to monitor local weather forecasts and take precautions.
The system is expected to move slowly, setting up a crippling ice storm that could knock out power to millions from northeast Georgia to southern Virginia Saturday night through early Monday morning.
Cities including Charlotte, Greenville, Winston-Salem and Greensboro are forecast to see ice accumulations of a quarter to a half an inch through Sunday night, alongside wind gusts of up to 40 mph that could take down trees and power lines in the region.
The National Weather Service has issued an ice storm warning for portions of South Carolina, in effect through early Monday, with temperatures likely to remain sub-freezing until the start of next week.
In the southern Appalachian Mountains, the snow totals will go up as quickly as the elevation does. Asheville, North Carolina, for example, is forecast to pick up 8-12 inches, but could reach 20 inches at elevations above 4,000 feet.
Mid-Atlantic and Northeast
The storm will turn northeastward to the East Coast on Sunday and Monday.
Some snow will fall in major metro areas, but a change to rain will hold down the accumulations. Washington could get 2-4 inches, while Philadelphia could get 1-2 inches. New York and Boston are expected to get about an inch each.
Heavier snow is expected elsewhere, with more than a foot expected in some locations.
Snowfall intensity in the region may be heavy enough to evade significant icing, but NWS Baltimore warns that untreated surfaces may still lead to dangerous travel conditions where ice accumulates.
The majority of accumulating snowfall will occur Sunday afternoon through Monday morning.
Interior cities such as Charleston, Pittsburgh, Buffalo, Syracuse and Burlington, Vermont, will see the heaviest snow.
Prior to the snow event moving into the region, the Northeast will experience cold temperatures and dangerous wind chill.
Wind chill alerts are in effect for nearly 20 million people Saturday, as feels-like temperatures could drop as low as 40 to 45 below zero in parts of the Northeast.
Alongside the snowfall potential, strong winds from the east associated with the storm system could cause major coastal flooding of up to 3 feet above ground in some areas along the Northeast coast during high tide.
The timing of winds shifting from the east to the south will largely determine the severity of flooding, with moderate flooding potential if winds shift prior to high tide.
“Widespread moderate to locally major flooding of vulnerable areas is possible near the waterfront and shoreline, including roads, parking lots, parks, lawns, and homes and businesses with basements near the waterfront,” the NWS in New York said Saturday.
Inundation could cause road closures and structural damage along the Atlantic coastline.
CNN meteorologists Allison Chinchar, Chad Myers, Dave Hennen, Monica Garrett, and Haley Brink contributed to this story