If you're one of the 112 million Americans traveling for Christmas, a soaking rainstorm could lead to air and road headaches across a large part of the southern and eastern U.S. later this week.

In many ways, thanks to mild temperatures, the storm looks to be quite similar to the one that drenched the eastern U.S. over the past few days: Lots of rain, but little in the way of snow or ice.

The storm should start to ramp up in intensity by Thursday, which is expected to be the busiest travel day of the season this year, according to AAA.

Folks traveling for the holidays will have lots of company this year: 112.5 million travelers are expected to take to the nation’s runways, roads and rails, AAA said. This "represents a 4.4 percent increase over last year and the most since AAA has been tracking holiday travel," the organization said in a statement.

On Thursday, rain is likely from the Southeast to the Mid-Atlantic and Ohio Valley, weather.com said. Some strong thunderstorms could also wallop parts of Florida, which would lead to airline delays in Tampa, Orlando and Miami.

AccuWeather meteorologist Maura Kelly warned that "flooding will once again be a concern across the Southeast, especially in areas already experiencing minor to moderate river flooding from the last round of rain."

Soggy conditions will continue for most of the East Coast by Friday, including the Northeast and New England. The storm will move away on Saturday, and clear sailing is expected for most of the East on Saturday.

The other travel trouble spot this week will be in the northwestern U.S., where a series of storms are forecast to pelt the region with rain and snow throughout the week and into the weekend. As much as 5 to 8 inches of rain is expected to drench coastal Washington and Oregon, weather.com said.

Most of the central and southwestern U.S. should see dry weather this week.

Temperature-wise, a mild week is forecast from coast-to-coast; above-average readings are likely. No big cool-down is likely in the days just before Christmas, which means chances for a white Christmas are very low for most of the nation.