Mount Rushmore National Memorial closed because of the icy, blinding weather in South Dakota's rugged Black Hills. Temperature plummeted as the storm moved eastward and wind gusted to more than 60 mph.
Some residents of hard-hit northeast Wyoming said they had heeded forecasts and stocked up on groceries.
"We are well prepared for a day or two of blizzard conditions," Marcia Shanks said in a telephone interview from her home in Gillette.
The National Weather Service posted a blizzard warning for eastern Wyoming and western sections of South Dakota and Nebraska, with a winter storm warning for much of central Wyoming and mountain sections of Colorado. Tornado watches were issued for eastern sections of South Dakota and Nebraska.
Wyoming shut down a 100-mile section of Interstate 90 between Sheridan and Gillette, and South Dakota closed the gates on a 100-mile stretch of the same highway from the Wyoming state line to Wall. Parts of I-80 in southeast Wyoming and I-25 in central Wyoming also were closed.
No-travel advisories were issued for parts of central and northeast Wyoming and northwest South Dakota. Colorado closed about 30 miles of state highway in that state's northeast corner.
Numerous schools called off classes altogether or closed early.
The weather service said accumulations of up to 20 inches were possible in parts of Wyoming and northwest South Dakota, but 30 to 40 inches was possible in the northern Black Hills, where Rapid City, S.D., recorded a gust to 63 mph.
The storm was fueled by moist air flowing in from the south and much colder air from the north, the weather service said.
"To give you an idea of the storm's intensity, it's 28 degrees at the Rapid City airport and 64 at Winner (S.D.). That's a distance of 170 miles," Susan Sander of the weather service said at mid-afternoon in Rapid City. Just 24 hours earlier, Rapid City had measured a record high of 77 degrees.
About 20 miles southwest of Rapid City, Mount Rushmore as closed because of the storm, said Superintendent Gerard Baker.
Intense spring snowstorms are common in Wyoming, said weather service meteorologist Andy Church.
"It looks pretty average in terms of how we measure intensity," he said of Monday's storm.
The spring storm came in the midst of calving season for cattle ranchers.
"The challenge we have is when the calves are born they're obviously wet to begin with. Then with the cold and the wind it just makes it hard to get them dried off and warmed up. That's critical to their surviving," said Adele Harty, an Extension Service livestock educator at Philip, S.D.
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