(CNN) -- Parts of Arizona will remain buried under snow Monday as a surprising late-winter onslaught paralyzed travel and closed schools. Yet much of the eastern two-thirds of the country will continue to enjoy unseasonably warm temperatures, a day before spring officially starts.
The National Weather Service issued a winter storm warning for the mountains of central and eastern Arizona through early Monday.
"Expect widespread snow across northern Arizona into Monday with extremely hazardous driving conditions, especially in the mountains," the weather agency said.
The city of Flagstaff is still digging out of 10 to 14 inches of snow from the weekend, which prompted school closings in the city for Monday. The city of Prescott received 8 to 12 inches.
The heavy snow and blustery winds also forced authorities to close 180 miles of Interstate 40 in northern Arizona on Sunday until further notice, the Arizona Highway Patrol said.
Brandon Neuman of Flagstaff produced a time-lapse video of about a foot of snow falling on his backyard deck in seven hours.
"The other day it was 65 degrees, next day it is snowing, so it's been crazy," Neuman said. "It killed a lot of people's travel plans because the highways are a mess."
But in eastern parts of the country, balmy conditions prevail, with temperatures well above average from Texas and the Midwest all the way to the East Coast.
Meanwhile, officials in southwestern Nebraska, will try to assess Monday the damage left by a pair of suspected tornadoes Sunday night.
Daniel H. Guenthner, emergency management director in Lincoln County, said he received reports of structures destroyed and 15 Union Pacific rail cars overturned at local rail yards after the two suspected twisters struck North Platte, Nebraska, at the same time.
Guenthner reported no fatalities and three injuries, one of which occurred when an 18-wheeler overturned.
He said the casualty toll is low because "the warning sirens went off early, and people took cover." But the storm left a debris field several miles long, as well as downed power lines, he said.