More than 1,000 flights were canceled across the U.S. as a winter storm moved into the South on Tuesday, just two weeks after Atlanta became a national punch line when a few inches of snow crippled the city.

The storm could be a "catastrophic event" reaching "historical proportions," the National Weather Service said in its warnings. Rain was falling Tuesday morning in Atlanta, with snow in north Georgia, and schools were canceled. Forecasts call for sleet and freezing rain Wednesday.

Downed power lines and icy roads are a major worry. Salt trucks, snow plows were ready to roll and the National Guard has 1,400 four-wheeled drive vehicles to help anyone stranded.

Before a single drop of freezing rain or snow fell, crews with Atlanta's Department of Public Works were already pre-treating roads and city officials said they were working with state and county officials to coordinate a joint emergency response plan ahead of the storm.

Georgia Gov. Nathan Deal declared a state of emergency for nearly a third of the state on Monday, as schools announced early that they would close Tuesday, and tractor-trailer drivers were handed fliers about the weather and a law requiring chains on tires.

"We are certainly ahead of the game this time, and that's important," Deal said. "We are trying to be ready, prepared and react as quickly as possible."

That kind of reassurance was a hard sell with some.

"I'm not counting on it," said Terri Herod, who bought a large bag of sand and a shovel at local hardware store. "I've been in Georgia on and off for 20 years. It's usually the same scenario: not enough preparations and not enough equipment."

The flight-tracking website FlightAware.com said more than 1,100 flights were canceled as of Tuesday morning, along with more than 2,600 delays. Hartsfield-Jackson Atlanta International Airport, the main hub for Delta Air Lines, led the nation in Tuesday flight cancellations with 217.

Delta is offering customers expecting to travel through several Southeastern cities between Tuesday and Thursday the opportunity to make free one-time changes to their itineraries, whether or not their flights have been canceled.

The waiver applies to travelers passing through Atlanta, North and South Carolina, Huntsville, Ala. and Norfolk, Va.

Other parts of the South were expected to get hit as well. Alabama, which saw stranded vehicles and had 10,000 students spend the night in schools during the January storm, was likely to get a wintry mix of precipitation. Parts of Mississippi could see 3 inches of snow, and a blast of snow over a wide section of Kentucky slickened roads and closed several school districts. South Carolina, which hasn't seen a major ice storm in nearly a decade, could get a quarter to three-quarters of an inch of ice.

With many at home instead of work or schools, the biggest threat in the current storm could be power outages. Forecasters say they're likely to be widespread as ice builds on trees and power lines. The ice threat is expected to begin in Georgia overnight. As much as 9 inches of snow could fall in parts of north Georgia by Wednesday night.

The memories of the last storm were too fresh for some. Late last month, students were trapped on buses or at schools and thousands of cars were abandoned along highways as short commutes turned into odysseys. One woman gave birth on a jammed interstate.

In the chaos, though, there were stories of Southern hospitality — people opening up homes and businesses to help the stranded. Officials reported one accident-related death.

People around Atlanta planned to stay off the roads, which couldn't be treated last time because there were too many cars stuck on them.

"Basically, everyone from the office is going to be working from home" on Tuesday, Dakota Herrera said as he left a downtown car park on his way to the office Monday.

Deal was doing many things differently. He opened an emergency operations center and held two news conferences before the storm. When the Jan. 28 storm hit, Deal was at an awards luncheon with Mayor Kasim Reed, who was named a magazine's 2014 "Georgian of the Year."

Reed had just tweeted: "Atlanta, we are ready for the snow."

This time, the mayor made no such predictions. Instead, he said he was in contact with school leaders and the city had 120 pieces of equipment to spread salt and sand and plow snow.

"We are just going to get out here and, flat out, let our work speak for itself," Reed said.

During the last storm, Deal and Reed didn't hold their first news conference until hours after highways were jammed.

Much is at stake for the governor, a Republican who is up for re-election, and Reed, who is seen as a rising star in the Democratic Party and has aspirations for higher office. Both took heat from residents, forecasters and even comedians during the last storm.

The governor apologized and announced the formation of a task force to study the problems. He also called for various reviews and wants a new public alert system for severe weather, similar to what's used for missing and endangered children.

Aaron Strickland, emergency operations director for Georgia Power, said the utility was bringing in crews from Florida, Texas, Oklahoma and Michigan.

"Ice is probably one of the worst events we face," Strickland said. "When you look at the types of ice we are talking about, it's catastrophic."

The Associated Press contributed to this report.