More than a million people across the Northern and Central Plains remained under blizzard or ice storm warnings early Tuesday, as heavy snow, freezing rain and powerful winds created treacherous road conditions that forecasters said could last through early Wednesday.
As of Tuesday morning, parts of Nebraska and South Dakota had recorded about four inches of snow, though strong winds prevented accurate readings, said Amanda Viken, a meteorologist at the National Weather Service’s office in North Platte, Neb. Some towns in southeastern South Dakota had received up to a foot of snow since Monday, according to the National Oceanic and Atmospheric Administration.
Up to four more inches of snow was expected through Tuesday evening in western South Dakota, western Nebraska, far eastern Wyoming and northeastern Colorado, the National Weather Service said. In areas where snowfall had stopped or slowed, freezing temperatures and strong winds could cause icy roads and whiteout conditions throughout the day, forecasters said.
“It’s pretty slick out, and the visibility restrictions that we’re seeing with this strong wind aren’t helping,” Ms. Viken said.
A blizzard warning affecting more than 600,000 people in parts of five states early Tuesday — Colorado, Kansas, Nebraska, South Dakota and Wyoming — would be in effect until early Wednesday morning in part of the region, the Weather Service said. A storm is a blizzard when it contains large amounts of snow, winds over 35 miles per hour and visibility of less than a quarter mile for at least three hours.
More than half a million people were also under an ice storm warning early Tuesday in the Dakotas and a slice of western Minnesota. The Weather Service warned in an advisory that travel could be “very difficult” and that snow had reduced visibility.
The South Dakota Department of Transportation said in a news release that conditions were “approaching near zero visibility” on roads covered in snow and ice on Monday afternoon, prompting officials to close parts of Interstate 90 through Tuesday morning.
An accident involving several jackknifed tractor-trailers forced a section of eastbound Interstate 80 near York, Neb., to close for about three hours on Monday afternoon, the Nebraska State Patrol said. There were no injuries in the accident, which was partly caused by blowing snow and slick road conditions, Cody Thomas, a spokesman for the Nebraska State Patrol, said in a statement.
Mr. Thomas said that there had been about 60 “weather-related incidents” on Interstate 80 in Nebraska on Monday, mostly between Lincoln and North Platte.
“We’re urging all travelers to assess whether or not their travel is absolutely necessary before hitting the road,” he said.
Forecasters warned that power outages were possible, particularly in South Dakota, as strong winds could damage trees and knock down power lines. As of early Tuesday, though, there were no reports of widespread power outages, according to PowerOutage.us, which tracks the utility industry.
The impact on air travel appeared to be relatively modest at the outset of the storm. About 170 flights within, into or out of the United States had been canceled as of Monday night, according to FlightAware. About 2,720 flights across the country had been delayed.
Holiday travelers who planned to hit the road on Tuesday should take caution on the road, said Matthew Meyers, a meteorologist at the Weather Service office in Sioux Falls, S.D. In the southeastern part of the state, temperatures were expected to remain below freezing, causing much of the rain that had fallen overnight to refreeze.
“If they can they should take it pretty slow,” he said. “It’s going to be slick out there.”
Eduardo Medina contributed reporting.