A powerful late winter snowstorm intensified over the central Rocky Mountains on Sunday with heavy snow and wind leading to airport and road closures, power outages and avalanche warnings in parts of Colorado, Wyoming and Nebraska.

The National Weather Service in Wyoming called it a “historic and crippling” winter storm that would cause extremely dangerous to impossible travel conditions through at least early Monday.

Major roads southeast of a line that crosses diagonally from the southwest corner of Wyoming to its northeast corner were closed Sunday, including roads in and out of Cheyenne and Casper.

More than 2 feet of snow had fallen just outside Cheyenne by 9:30 a.m. Saturday, the weather service reported, while other areas around the city had seen 16 to 19 inches. A SNOTEL site at Windy Peak in the Laramie Range reported 52 inches of snow in a 24-hour period ending Sunday morning, the weather service said.