Hartsfield-Jackson International Airport will be hobbled by another wave of flight cancellations Thursday morning, but its two biggest carriers expect to begin returning to normal operations as temperatures rise in the afternoon.

With ice still on roads and weather conditions dicey, airport officials estimate about 60 to 70 percent of the 2,200 to 2,400 regularly scheduled flights will operate tomorrow, while the rest will be canceled.

Delta Air Lines plans to restart Atlanta operations gradually, with some arrivals mid-morning, followed by departures starting after 2 p.m. The ramp-up to regular operations will continue into Friday.

Southwest Airlines and its AirTran Airways subsidiary canceled all departures until 1 p.m. Thursday, when they expect to resume a normal schedule.

Airline and airport officials warned travelers to check their flight status before going to the airport and to be sure their airline has their contact information for notifications. Delta also extended its waiver of change fees for those who want to alter their flight plans.

On Wednesday, some 2,000 Atlanta flights were canceled and only about 100 took off, according to Hartsfield-Jackson officials.

Delta operated only a few dozen Atlanta departures and canceled some 1,700 flights Wednesday. Southwest and AirTran, which together operate more than 300 daily Hartsfield-Jackson flights, canceled all Atlanta flights Wednesday.

One reason Delta canceled so many flights was to move planes out of Atlanta so they wouldn’t be covered with ice and frozen to the ground, Delta spokesman Morgan Durrant said.

This storm’s type of frozen precipitation is “extremely challenging” to treat with anti-icing solution, he said.

All in all, by Thursday afternoon the storm is likely to have disrupted hundreds of thousands of travelers’ plans across the country and the world, with the world’s busiest airport at the center of the impact.

The cancellations prevented any huge pileup of fliers at the airport Wednesday, but dozens of travelers have spent the night there, as have hundreds of workers who needed to be in place for the next day.

It started in earnest Tuesday night, when some 175 travelers stayed the night in the terminal and concourses, curling up in chairs and sprawling on the carpet.

Workers slept in locker rooms, on cots and inflatable mattresses in offices.

Some travelers settled into the airport to wait for their Thursday flights.

“We figure it’s just easier to stay here than get a hotel. Plus it’ll make a good story,” said traveler Jack Frederick, of Wisconsin.

Josh Atkins, trying to return home to Austin, Texas, went to the airport Tuesday night from his hotel. “I was afraid I’d get snowed in so I came here,” he said.

Some travelers were exasperated with the flight cancellations.

“We wonder if they’re being too cautious,” said Frederick’s wife, Kathy. En route to the South Carolina coast for a wedding and vacation, she said, “we had no other option but to come out here and hope for the best.”