A powerful late winter snowstorm intensified over the central Rocky Mountains 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. Denver International Airport closed its runways just before noon Sunday and the Wyoming Department of Transportation suspended plowing in the Casper area Sunday after several plows went off the road due to low visibility.