CNN
—

A storm and the first chill of winter will combine to create Thanksgiving travel headaches in the eastern half of the United States as Mother Nature dishes out a slew of sloppy weather.

The storm will roll through parts of the Midwest and South Wednesday night and spread across the East on Thanksgiving Day. At the same time, frigid air will rush into the US, like shoppers clamoring for Black Friday deals.

The exact path of the storm is still unclear and will determine which areas get holiday snow and which areas end up with a wet, gloomy mess. But there are two scenarios at play, and in each scenario there will be a disruptive storm for last-minute travelers.

In the first scenario, a storm develops in the Plains on Wednesday, strengthening eastward. It should become quite a force Wednesday evening as it spreads rain from the Midwest to the South.

Once it reaches the Appalachians, it would turn northeast and follow along their spine Thursday, tapping into some cold Canadian air before heading toward the New England coast overnight.

This would bring a round of heavy, wet snow to the higher parts of the interior on Thursday, while the lower parts will be drenched by rain.

Wind speeds are also expected to increase in the east on Thursday, with widespread gusts of up to 30 km/h possible. Higher gusts are possible for areas closer to the coast, especially from the Carolinas to southern New England.

Gusty winds could disrupt both air and road traffic for truly last-minute travelers on Thanksgiving Day. The combination of wet weather and high winds can also topple trees or power lines.

The storm was expected to reach northern Maine on Friday morning and leave the US shortly afterwards. This should produce mostly dry, but still breezy, weather for the East for Friday and the weekend.

Another possible scenario would be for the heaviest rain and risk of sleet to shift largely out of the Northeast, creating a much wetter Thanksgiving for the mid-Atlantic instead.

In this scenario, the storm would develop around the Mississippi or Tennessee valleys late Wednesday evening. It would then travel slowly through the mid-Atlantic Ocean through Thursday night, reaching the Atlantic Ocean Friday morning.

This would bring more rain to the Southeast and Mid-Atlantic on Thursday, while limiting the potential for drenching rain and snow accumulation in the Northeast.

But how close to the coast the storm lingers when it reaches the Atlantic Ocean on Friday will impact post-holiday travel.

A mix of rain and snow could develop in the Northeast and creep closer to the coast as the storm hugs the coast and heads toward New England. This could lead to a sloppy mess Friday at Boston-area airports and for people traveling along the nearby Interstate-95 corridor.

Wet weather would be minimal for these areas as the storm moves further away from the coast on Friday.

A widespread flow of cold, Canadian air is moving into much of the U.S. regardless of the eventual track of last week’s storm.

Cold air will move into northern states early this week before a significant flow of winter-like air becomes widespread on Thursday.

Chicago will struggle to reach the mid-30s on Thanksgiving Day — a temperature better suited for late December. Parts of North Dakota will barely reach the teens and will look more like January.

Millions from coast to coast will be freezing on Friday.

High temperatures as far south as the Gulf Coast will likely be 10 degrees or more below normal, and some locations may not exceed 60 degrees.

Many regions in the central and eastern US will experience their coldest conditions yet this season.

Philadelphia hasn’t recorded a high in the 30s since February, but could get close on Saturday or Sunday. The same can be said of New York City.

The rush of frigid air later this week will also flip the switch on the Great Lakes lake effect snow machine. The cold Canadian air flowing over the record warm lakes will set the stage for lake effect snow, which could last into next week in some areas.

Cold air will linger over much of the East as the calendar shifts to December and could last until the first week of the new month, according to forecasts from the Climate Prediction Center.