Parts of the Northeast are preparing for winter weather this week. More than 122 million Americans are expected to travel at least 50 miles for Christmas and New Year's holidays this year. Periodic snowfall rates of more than an inch per hour are likely, resulting in totals of 5 to 10 inches with locally higher amounts possible.

Worried about your upcoming holiday travel? Here are regions that are most at risk of winter storms this Christmas, according to forecasts.

On Tuesday, Dec. 16, the National Weather Service (NWS) issued a Winter Weather Warning for a significant portion of Washington, warning that the area could be hit with up to 36 inches of snow and wind gusts up to 65 miles per hour.

After an active stretch of winter weather, things are finally starting to calm down. The next several days will feature milder temperatures and only minor, fast moving systems with light precipitation at times.

A winter storm warning was issued by the National Weather Service on Sunday at 2:22 a.m. valid from Monday 4 p.m. until Saturday 7 a.m. for Oswego, Jefferson and Lewis counties.

Central Pennsylvania will see a variety of weather this week, from light snow to a couple of cloudy and chilly days, all capped by a potentially significant winter storm on Friday.

A late-week storm system is expected to bring a snow, rain and ice to the Detroit area, according to the National Weather Service.

On the opposite coast, Southern California faced an even more destructive threat. Heavy rain from an atmospheric river system caused flooding and mudslides, particularly in areas still scarred by wildfires. Evacuation orders were issued as debris swept across roads and into neighborhoods, forcing emergency crews into constant response mode.

COLUMBIA, S.C. (WIS) - Between December 25-27 in 2010, a winter storm produced snow across much of the Carolinas for the Christmas holiday. This was courtesy of a cold core low-pressure system that had a low of moisture with it. It drifted northeastward out of the Gulf towards the Carolinas where it started to track up the East Coast.

We may not see a white Christmas this year, but just wait a day, and some parts of Eastern Pennsylvania could see up to four to six inches of snow, experts project.