The storms in the Midwest and Northeast had a ripple effect on travel in Southern California. More than 1,300 flights were canceled nationwide. Many aboard incoming flights to Los Angeles International Airport said their planes were delayed.
Powerful snowstorms battered the gulf coast in Texas, Louisiana, Mississippi, and Alabama, causing the fatalities and triggering more than 30 rare winter tornadoes.
Mobile, Alabama was the biggest city hit by numerous twisters. Several twisters roared through Mobile, tearing down parts of some downtown businesses and other establishments.
Scott Rye, a senior warden at Trinity Episcopal Church, said a large section of the church's roof was missing after the tornado passed.
Another twister hit Pearl River County in Mississippi, blowing insulation into trees and peeling back walls of homes.
Mississippi Gov. Phil Bryant declared a state of emergency in eight counties with more than 25 people reported injured and 70 homes left damaged.
Blizzard warnings were issued amid snowy gusts of 30 mph that blanketed roads and windshields, at times causing whiteout conditions.
"The way I've been describing it is as a low-end blizzard, but that's sort of like saying a small Tyrannosaurus rex," said John Kwiatkowski, a meteorologist with the National Weather Service in Indianapolis.
The same fast-moving storms brought blizzard conditions to parts of the country's midsection causing a 21-vehicle pileup in Oklahoma City that injured 10 people.
In Texas, authorities said high winds knocked over a tree, killing one man near Houston. Investigators said he tried to move a downed tree blocking the road when the another tree snapped and fell on him.
The storm reportedly left many Christmas celebrations in the dark in Texas, Oklahoma, Mississippi, Louisiana and Alabama. In Arkansas, more than 200,000 customers could be left without electricity for more than a week after 10 inches of snow coated power lines and snapped poles.
As the system heads east, it's bringing treacherous conditions the day after Christmas. Post-Christmas travelers were advised to brace for flight delays and dangerous slick conditions on the road. More than 1,200 flights across the nation were canceled as of Wednesday afternoon, according to the flight tracker FlightAware.com.
Tornadoes in December are not unheard of. The NWS says in 2009, 22 tornadoes touched down on Christmas Eve along the Gulf Coast. The last fatal storm was in 1982 when 20 tornadoes hit Oklahoma, Missouri, Arkansas, Tennessee, and Mississippi, killing three people and injuring 32.
The Associated Press contributed to this report.