OMAHA, Neb. – A powerful winter storm that covered parts of Colorado with up to 6 feet of snow crept east across the Plains on Saturday, making travel treacherous, downing power lines and knocking out electricity to thousands.

Nebraska got more than a foot of snow, and forecasters predicted the storm would drop several inches Saturday in central Iowa before gradually weakening as drier air mixes in and the front continues east.

The storm caused the most problems in Colorado, where Interstate 70 was closed between Denver and the Kansas border until Saturday morning. More than 600 flights were canceled Friday in Denver.

All winter storm warnings expired in Colorado by Saturday afternoon, but warnings remained in place for eastern Nebraska and central and southwestern Iowa.

The National Weather Service said snowfall across the Denver area ranged from 14 to 20 inches. Nearly 4 feet covered the Pinecliffe area, while there was 18 inches near Boulder and 14 inches in the capital city itself. Several towns in eastern Colorado reported more than a foot of snow.

Ski resorts that have suffered below-normal snowfall this year welcomed the snow, but some benefited more than others. Echo Mountain near Denver received 55 inches of new snow, but the storm only dusted larger resorts in the central Colorado mountains.

The downside of all that fresh snow is greater potential for avalanches. The Colorado Avalanche Information Center reported 2 feet or more of new snow could easily overrun the weak, existing snow pack.

The highways in Nebraska and Iowa generally remained open during the storm except when accidents or downed power lines blocked the way, but officials urged people to stay off the roads if they didn’t have to travel.