Blizzard Conditions Threaten to Disrupt Travel Across Northern Plains

More than 725,000 people in the northern Great Plains were under a blizzard warning on Monday, as forecasters warned that heavy snow and powerful winds could disrupt flights and create treacherous road conditions.

Central South Dakota, where more than a foot of snow was possible, was expected to bear the brunt of the storm. Hazardous conditions were also forecast across portions of east-central and southeastern South Dakota, southern North Dakota and Nebraska, said Kyle Weisser, a meteorologist with the National Weather Service in Sioux Falls, S.D.

Parts of South Dakota were expected to receive up to 13 inches of snow, with wind gusts as high as 55 miles per hour, according to the Weather Service.

“Travel could be very difficult to impossible,” meteorologists warned in an advisory, noting that “widespread blowing snow” could significantly reduce visibility.

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.

The heaviest snowfall in central South Dakota was expected from 2 p.m. to 10 p.m. local time, the Weather Service said. Strong winds and snow could linger into the night, especially in the central part of the state, forecasters said. A blizzard warning was in effect through late Tuesday night.

North Dakota and Nebraska will get more freezing rain, causing slick conditions, meteorologists said.

The effects of the storm were expected to be felt as far west as Colorado and as far south as Kansas, where about eight inches of snow and wind gusts of up to 60 m.p.h. were possible in places. Blizzard conditions in northern and northwestern Kansas were expected until early Wednesday morning, according to the Weather Service.

Holiday travelers who had expected to hit the road on Monday afternoon might want to adjust their plans, Mr. Weisser said.

“Depending on which direction you’re going, if you haven’t left yet, you might want to wait until tomorrow,” he said.

Temperatures will begin to rise Monday evening in eastern South Dakota and in parts of Minnesota and Iowa, and driving conditions will improve in those areas, Mr. Weisser said. Strong winds, however, could still be an issue for drivers, he said.

“Even if there’s not a lot of falling snow, you can still have significantly reduced visibility if the wind is blowing 30 to 40 miles an hour,” he said.

The impact on air travel appeared to be relatively modest at the outset of the storm. Fewer than 150 flights within, into or out of the United States were canceled as of early Monday afternoon, according to FlightAware. Nearly 1,700 flights across the country were delayed. Sioux Falls Regional Airport encouraged travelers to check with their airline for word of any cancellations or delays.