ATLANTA — A vast swath of the South was hunkering down Wednesday in the face of what the National Weather Service called "mind-boggling if not historical" snow and ice.
The "potentially historic" winter storm threatened to knock out power for hundreds of thousands, and travel conditions were already dicey in many areas early Wednesday.
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From Texas to Georgia and up to the Carolinas, roads were slick with ice, and thousands of customers were already without power early Wednesday as a wintry mix fell in many areas.
"The storm is on track," National Weather Service meteorologist Bruce Terry said. "That much freezing rain and sleet can be devastating. It will mean downed trees and powerlines."
As the storm heads north and east, ice will give way to snow. Washington, D.C., Baltimore and Philadelphia will see 4-8 inches of snow starting Wednesday night and all day Thursday, Terry said. New York and Boston can expect 3-6. But areas north and west of all those cities could see a foot or more of snow.
Early Wednesday, ice was beginning to accumulate on metro Atlanta roads and interstates. Georgia Department of Transportation crews were working to keep the roads open for people who need to travel for essential purposes.
But the region is a virtual ghost town. Most residents have stocked up on food and essentials. They are heeding the repeated, urgent warning of authorities and are staying home. All area schools, non-essential government operations and most businesses are closed.
Georgia Gov. Nathan Deal has declared a state of emergency for 91 of the state's 159 counties as ice from sleet, snow and freezing rain is expected to cause massive power outages. He said the National Guard opened 65 emergency shelters, and seven more were open at state parks along Interstate 20.
About 80,000 people were without power in the state. "We have about 60,000 in metro Atlanta, mostly on the south side of metro Atlanta," said Georgia Power spokesman Brian Green. Hundreds of lineman are working and on call, and mobile showers, dining hall and kitchen have been set up in the Mall of Georgia's parking lot -- although a kitchen worker said defrosting ribs when it's frozen outside has proven difficult.
The Georgia Department of Transportation was warning of "extreme black ice," more than 7 inches of snow across northeast Georgia and up to an inch of ice accumulation north and south of the Interstate 20 corridor. "This is a very dangerous ice storm and we strongly encourage the public to stay off the roads unless it is an extreme emergency," said state DOT Commissioner Keith Golden.
Atlanta's Hartsfield-Jackson International Airport was operating on a minimal schedule Wednesday, with 2,200 flights canceled and only about 300 expected to operate.
Icy roads and downed trees were being reported in Augusta and other cities east and south of metro Atlanta.
The weather in the region is expected to worsen throughout the day and into Thursday.
Georgia Power was already reporting power outages around the state as emergency management workers waited to spring into action as rain — along with temperatures — fell, potentially leading to "catastrophic" ice conditions that were forecast to hit the region.
Shreveport, La., Mayor Cedric Glover tweeted that "Due to inclement weather the city of Shreveport will be closed Wednesday." In one hour Tuesday afternoon, the small Louisiana city had eight car wrecks, a bus wreck and an overturned garbage truck, Glover said.
Eli Jacks, a meteorologist with the National Weather Service, said forecasters use words like "catastrophic" sparingly.
"Sometimes we want to tell them, 'Hey, listen, this warning is different. This is really extremely dangerous and it doesn't happen very often,'" Jacks said.
Zach Steenberger, 19, and his mother, Vanessa Bray, 48, both of suburban Atlanta, shopped at Home Depot on Tuesday for last-minute storm preparations: a power saw, kerosene and batteries.
"I'm really ready for summer to get here," Bray said.
The storm, named Pax by The Weather Channel, is at least the third this winter to lash the South. Earlier in January, temperatures dropped to single digits as far south as Atlanta and Birmingham.
After walloping the Southeast with ice and freezing rain, this latest storm is forecast to move up the East Coast later Wednesday and into Thursday, potentially dropping as much as a foot of snow all the way from Virginia to New England.
Heavy snow is forecast just west of the Interstate 95 corridor from Washington to Boston, and continuing up into Maine.
"Airports from Washington, D.C., to Baltimore, Philadelphia, New York City and Boston will experience trouble with this storm," said AccuWeather meteorologist Alex Sosnowski.
Contributing: John Bacon, Talia Richman, Kim Hjelmgaard and William M. Welch; WXIA-TV in Atlanta