A blizzard has roared into North Dakota today and is expected to dump up to a foot of snow in neighbouring Minnesota before moving east over the mid-Atlantic states, where it could bury the Washington area with its biggest snowfall of the winter, the US National Weather Service said.
Blowing snow and drifts up to 0.9 metres left parts of Montana and the northwest North Dakota oil region with visibility at 400 metres under blizzard conditions that were expected to last into Monday night (Tuesday evening NZT), the weather service said.
The North Dakota transportation department was recommending "no travel" on roads across the north-western part of the state where there is a blizzard, stretching along the northern edge of the state across to roads north of Grand Forks.
Up to 38cm of snow was expected in north-western North Dakota and 23cm in the Grand Forks area, on the eastern border with Minnesota. But the state took the latest storm in stride.
"It's a normal late winter storm for us," said Adam Jones, a meteorologist with the National Weather Service in Bismarck.
The Minneapolis and St Paul metropolitan area was dusted by 2.5cm to 5cm of snow on Monday from a separate storm system, and up to 25cm was expected from the main winter storm, mostly overnight into Tuesday morning, the weather service said.
The storm was expected to dump heavy snow along the Minnesota and Wisconsin border, with up to 30cm in the far south-eastern corner of Minnesota, before heading across southern Wisconsin and into Illinois.
Minneapolis-St Paul International Airport had 107 flight cancellations on Monday and O'Hare International Airport had 65, FlightAware.com reported.
Traffic pile-ups in Colorado
Meanwhile, heavy snow and high winds were blamed for two major traffic accidents in the Colorado mountains, near the ski resort of Vail, involving more than 50 vehicles.
Three people were hospitalised from a 25-vehicle chain- reaction crash that closed a stretch of Interstate 70, the Summit County Sheriff's Office said in a statement.
"None of the injuries were reported to be serious," the statement said.
A second pile-up about 27km away on the same interstate involved 29 vehicles, with no reported injuries, the sheriff's office said.
The Colorado Department of Transportation said several portions of the interstate along the mountain corridor about 160km west of Denver were closed for several hours on Monday afternoon following the accidents. The highway was reopened in both directions by 5.30pm local time.
The snow was part of a fast-moving storm that swept through Colorado, dumping up to foot of white stuff in the north-central mountains, and dusting the ground in the Denver metropolitan area.
Overall, the storm was expected to stretch across North Dakota, much of Minnesota, northern Iowa, western Wisconsin and then into northern Illinois.
North-eastern Illinois, including Chicago, was forecast to receive 15cm to 25cm of snow overall, starting late Monday and spanning the morning and more intensely the evening rush hours.
The snow was expected to become more intense toward Tuesday morning with the heaviest accumulations during the day on Tuesday, the weather service said. The storm was forecast to move east, reaching the Ohio Valley, the mid-Atlantic states and the Washington area later on Tuesday and into Wednesday.
"This will be certainly the biggest snowstorm for the winter in this area," said National Weather Service forecaster Bruce Sullivan, who is in Maryland.
Forecasts suggested the system could dump 20cm to 36cm of snow over parts of Maryland, West Virginia, Pennsylvania and Virginia, the National Weather Service said.
It will bring a cold, dry snow over the mountains of Virginia and a heavy, wet snow east of Washington, he said.
One of the more challenging aspects is predicting how much snow would fall on or east of heavily travelled Interstate 95 in Virginia and Maryland, forecasters said.