By Nicole Chavez, CNN
(CNN) -- A complex winter storm is moving through the central United States, threatening to impact holiday travelers, according to the National Weather Service.
About 15 million people from Arizona to Minnesota are under winter storm warnings or advisories through Saturday. A strong system is set to bring a mix of freezing rain, sleet and snow.
Some areas of Colorado could see near blizzard conditions on Saturday as strong winds could create blowing and drifting snow.
The National Weather Service in Colorado described the storm as a "complex storm system" and warned drivers of possible difficult travel conditions through the weekend.
This major storm already had people struggling to push cars out of the snow in California over the past two days and it could make holiday travel a nightmare to those in its path as it moves toward the Northeast over the weekend.
Heavy snow in Central US
Mountains across much of the Southwest, including New Mexico and Colorado, could see hefty amounts of snowfall through Saturday.
About 10-20 inches of snow are expected in the San Juan mountains in Colorado. In New Mexico, locations above 7,500 feet will see snow totals of 8 to 12 inches, forecasters said.
"If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency," the weather service warned residents.
But the storm will not only affect the Southwest. Forecasters say the storm will continue to intensify and move through the Plains and to the Upper Midwest on Saturday.
About 10-18 inches of snow are expected from Nebraska through the Dakotas and into northern Minnesota, CNN meteorologist Taylor Ward said.
Rain and thunderstorms in Mississippi
The storm will start approaching the South on Saturday and bring heavy rain to the Mississippi.
"The front will be interacting with much warmer air and a fetch of moisture from the Gulf of Mexico that will help to support the threat of strong severe thunderstorms and areas of heavy rainfall," the weather service said.
The 1-2 inches of rain expected are not considered to pose a flood threat, but it could challenge some holiday travelers.
By Sunday, the thunderstorms and rain will shift northeast into the Tennessee and Ohio Valleys, forecasters said.
US has seen holiday winter storms before
Several post-Christmas storms have rocked the country in the past several decades, the weather service said.
A storm moving north along the East Coast beginning on Christmas night 1969 became the third greatest snowstorm to hit Albany, bringing a total of 26.7 inches of snow, the weather service said.
Flights were cancelled Christmas night in 2002 and many travelers were left stranded at airports when a snowstorm hit the northeast bringing more than 20 inches of snow, the weather service said. The area was struck again by another storm just after New Year's Day.
In 2010, the days after Christmas brought wind gusts up to 70 mph and up to 2 feet of snow to the Northeast. Snowfall rates reached 1 to 3 inches an hour across the region, according to the weather service.
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