Coal Bank, Molas and Red Mountain passes on U.S. Highway 550 north of Durango were closed early Saturday after natural avalanches, according to the Colorado Department of Transportation.
The passes were closed shortly after 8 a.m., and there was no estimated time for reopening.
Lizard Head Pass on Colorado Highway 145 also was closed just before 9:30 a.m. for avalanche work, CDOT said.
Crews are waiting for conditions to improve to do avalanche control in those areas, CDOT spokeswoman Lisa Schwantes said.
U.S. Highway 550 is closed for 45 miles, from just north of Purgatory and continues to Ouray.
Road conditions began to worsen Friday evening, and chain laws went into effect shortly after 8 p.m. on the passes.
In the last 24 hours, Red Mountain Pass received 8 inches of snow, Molas and Coal Bank passes received 7 inches.
The San Juan Mountains are under a winter storm warning through 5 p.m. Saturday, with 10 to 20 inches of snow expected, according to the National Weather Service.
The warning area includes the towns of Silverton, Rico and Hesperus. Wolf Creek and Cumbres passes also are in the winter storm warning area.
Durango is expected to see a mix of rain and snow showers through Saturday, but with little accumulation. Widespread fog is expected early Saturday, the Weather Service said.
