Thanksgiving travel is officially underway, and AAA is predicting a record-breaking number of travelers. This week is also one of the busiest travel weeks at Philadelphia International Airport, according to officials.

Before the sun was up Monday morning, the lines were long at TSA checkpoints, but wait times dissipated throughout the day.

Nearly a million people are expected at the airport over the holiday travel period.

Most travelers Monday who spoke to CBS News Philadelphia said things went smoothly. That’s the hope for the rest of the week when volume picks up here and the weather takes a turn.

“Even if it’s really nice here, it just takes one thing to throw off that chain, and you could be later than you were planning to arrive,” Heather Redfern, a spokesperson for PHL, said.

Jana Tidwell with AAA Mid-Atlantic cautioned that the weather could be a factor later this week.

“There is a storm system that’s moving across the country, so all air travelers need to pay attention to that because that could disrupt things here,” Tidwell said.

The weekend after Thanksgiving will be the two busiest days at the airport, officials predict, and Wednesday comes in third with a little under 94,000 people expected to fly through PHL.

Nationwide, the TSA expects to screen nearly 18 million people from the Tuesday before Thanksgiving to the Tuesday after the holiday, while the FAA expects this will be the busiest Thanksgiving in terms of flights in at least 15 years.

Even more people are expected to travel by car, with AAA expecting 90% of all holiday travelers to hit the road.