Up to 2 ½ feet (0.61 meters) of snow was expected to fall in parts of eastern South Dakota and southwestern Minnesota, the National Weather Service said. More than 300 flights out of Denver were canceled on Wednesday, according to FlightAware.
South Dakota Governor Kristi Noem on Wednesday closed state government offices in 52 counties under a blizzard warning, according to a statement from her office. "We will set some records", said Mike Connelly, a weather service meteorologist in Aberdeen, South Dakota.
The National Weather Service Storm Prediction Center also posted its own announcement regarding the weather risks.
Transportation officials closed Interstate 29 from east central South Dakota to the North Dakota border and said other stretches of major interstates were likely to close as conditions deteriorated.
Two factors may limit the flooding effect, forecasters said.
Rain and then blowing snow was expected to hit the Rockies on Wednesday, before moving east into the plains, the NWS Forecast Office in Boulder, Colorado, reported. The Minnesota State Patrol responded to 213 crashes by early evening Wednesday.
Colorado Gov. Jared Polis activated the National Guard in case it's needed to rescue stranded motorists.
A cyclone last month dropped heavy rains over that region, causing extensive flooding along the Missouri River and more than $3 billion in damage to property and crops in Nebraska and Iowa.
It's rare enough to have one form inland, much less two in a month.
Meanwhile, about half of the flights at Denver International Airport were scratched ahead of the storm that approached a day after temperatures reached into the 70s and just after firefighters battled wildfires that prompted some evacuations. Roads will be slick as temperatures fall to around 20 degrees by morning.
In the Denver area, periods of snow will continue overnight with a couple of inches of snow.
April snow isn't unheard of there.
The snowfall could lead to additional flooding in the region. Paul; Rapid City and Sioux Falls, South Dakota; Rochester, Minnesota; Marquette, Michigan; Jackson Hole and Cheyenne, Wyoming; and Appleton, Green Bay, La Crosse, and Wausau, Wisconsin can rebook their trips through April 14. The storm has already taking shape and flooding risks will rise as the snow from the storm melts later in the week.
Travel both by air and ground will likely become impossible as heavy snow and strong winds will reduce visibility to zero.
In Iowa, Gov. Kim Reynolds urged Iowans to make preparations for flooding.
Winds gusted as high as 75 miles per hour - right at hurricane strength - in New Mexico, according to CNN meteorologist Taylor Ward.
The weather service posted an ice storm warning into Friday morning for a portion of southern Minnesota, saying up to three-fourths of an inch of ice could accumulate on power lines, leading to outages. So is much of the state, the high plains of Colorado as well as Kansas and Texas. To the south, a major wind storm is gathering steam.
United Airlines is waiving change fees for flights booked on Wednesday and Thursday.