UPDATE, 3:38 p.m.
U.S. Highway 550 over Red Mountain Pass will remain closed the rest of the night, as adverse weather conditions have made avalanche mitigation operations impossible to perform, according to the Colorado Department of Transportation.
High accumulations of snow, high winds, blowing snow and low visibility have forced maintenance personnel to leave the pass. Crews have reported more than 18 inches of new snow in the past few hours.
Southbound traffic will be stopped just south of Ouray at mile marker 92, while northbound traffic will be stopped just north of Silverton at mile marker 71. Motorists are encouraged to use Colorado Highway 145 via Telluride as an alternate north-south route.
There is no estimated time for reopening U.S. 550 over Red Mountain Pass.
An avalanche warning is in effect today through Wednesday morning for the northern San Juan Mountains, with forecasters saying heavy snowfall will trigger long-running, destructive avalanches.
The Colorado Avalanche Information Center issued the warning at 6 a.m. today, advising that "very dangerous avalanche conditions exist" and that recent avalanche activity suggests "large to very large avalanches are likely to slide today on all aspects at all elevations." Forecasters advised people to stay out of avalanche terrain today.
The warning comes two days after a group of backcountry skiers remotely triggered an avalanche from a few hundred feet away on Red Mountain Pass. The avalanche ran 800 feet wide and piled debris 25 feet deep, according to the CAIC, which called the avalanche "unsurvivable."
At least 10 people have died in avalanches in Colorado during the 2020-21 season, including five in the San Juans.