Eastbound lanes of Interstate 70 have been closed since 5:30 p.m. because of numerous accidents, with no estimated time for it to reopen, the Colorado Department of Transportation said Sunday night.
The combination of heavy snow, gusty winds and weekend ski traffic caused hours of congestion.
Eastbound travelers faced delays of more than two hours, as snow fell at a rate of an inch an hour Sunday afternoon, according to CDOT.
Metering to regulate the number of vehicles in the Eisenhower Tunnel ended at 9 p.m.
Traffic in the Colorado mountains was snarled by snow and wind. An avalanche closed U.S. 50 over Monarch Pass between Gunnison and Chaffee counties. Accidents closed in the interstate intermittently Sunday afternoon.
The weather is expected to last into Monday, with a winter storm warning in effect until 6 a.m. for north-central Colorado.
"Avalanche control may be required on any mountain road at any time," CDOT said Sunday night.
Areas of western Colorado have collected 6 to 30 inches of snow since Friday, with the highest amounts across the Front Range, Summit County and north of Rabbit Ears Pass, according to the National Weather Service.
The snow was being driven by winds of 20 mph to 30 mph, with peak gusts near 60 mph at timberline and along high mountain passes.
An avalanche warning is in effect for the Park Range, Flat Top, Front Range, Gore Range, Ten Mile Range, Ruby Range, the West Elk Mountains, Mosquito Range and Sawatch Range.
The warning includes areas near Steamboat Springs, Aspen and Gunnison, as well as Summit County.
"Avalanche conditions are very dangerous," the Colorado Avalanche Information Center in Boulder stated. "Natural and human-triggered avalanches are likely. Some avalanches may be very large and destructive.
"Backcountry travelers are advised to stay well clear of all avalanche terrain. Avoid traveling on or under steep slopes."
Snow in the mountains should decrease starting Monday afternoon and come to an end Monday night, although many areas could get an additional 1 to 4 inches Monday, forecasters said Sunday.
Snow and gusty winds could return to the mountains Wednesday and continue through the end of the week.
Clouds and fog, similar to Sunday's weather, should continue in the Denver region Monday, with a high temperature of just 31 degrees, forecasters said.
Sunny skies return Tuesday with a high of 47, according to the forecast. The city is expected to climb into the 50s Wednesday and stay in the upper 50s Thursday through next Saturday.
Average high temperatures in Denver this week are in the mid-40s, according to weather records.
Joey Bunch: 303-954-1174, firstname.lastname@example.org or twitter.com/joeybunch