Summit County and adjacent counties are experiencing severe winter weather, which has resulted in widespread road closures and extreme avalanche danger.

According to the Colorado Avalanche Information Center, avalanche danger is Extreme (5 of 5) above treeline, at treeline and below treeline: "Reports of natural avalanches running in all possible paths continue to stream in. Historic avalanches have been observed or triggered all week and will continue throughout the day. A second round of heavy snowfall and strong winds have created very unusual and extremely dangerous avalanche conditions. Natural avalanches have the potential to break widely across mountain faces and run down to the valley floor. Travel in, near, or below avalanche terrain is not recommended. This may include backcountry roads, trailheads, or any infrastructure below avalanche paths where avalanche mitigation is not occurring. Even low elevation avalanche terrain that rarely slides might today."

The National Weather Service has issued a Winter Storm Warning through 5 p.m., Thursday: "Today: Snow showers likely. Mostly cloudy, with a temperature falling to around 37 by 5 p.m. Breezy, with a west wind 9 to 17 mph, with gusts as high as 28 mph. Chance of precipitation is 60%. Total daytime snow accumulation of 1 to 2 inches possible. Tonight: A 30 percent chance of snow showers before 11 p.m. Mostly cloudy, with a low around 20. West wind around 7 mph. New snow accumulation of less than a half inch possible. Friday: Snow showers, mainly after 11 a.m. Some thunder is also possible. High near 41. South southwest wind 7 to 13 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. New snow accumulation of less than a half inch possible."

The Colorado Department of Transportation (CDOT) has enacted several closures of I-70 and other state highways. Highway status is changing frequently, so travelers should be sure to check CoTrip.org for the most current information. As of 1 p.m., Thursday, "Extended closures for avalanche mitigation ... I-70 closed from Copper to Vail for next 5 hours. I-70 open from Copper to Silverthorne. Loveland Pass is closed, probably for much of the day and into the evening. CO 24 is closed. WB Exit 232 (Empire Junction) is closed for mitigation at the Eisenhower Tunnel (local traffic Georgetown and Silver Plume)."

Local roads also have received significant snowfall, especially between Frisco and Hoosier Pass, with some areas receiving 18 inches or more overnight. Summit County Road & Bridge Department is working to clear County roads, prioritizing main arteries such as Swan Mountain Road. Progress has been slow, as the snow is heavy, wet and deep. It will take longer than usual for crews to reach roads in residential neighborhoods. On many roads, traffic has compacted the wet snow in many spots, leading to icy and snowpacked conditions. We are anticipating an extended closure of Dillon Dam Road, due to risks of rock fall and avalanches on the cliffs above the road just west of the dam. Road conditions in Silverthorne and points north are better than in the southern portions of the county. Summit County Road & Bridge and the Summit County Sheriff's Office recommend avoiding vehicle travel in Summit County if possible. If you do travel, please use an abundance of caution, travel at low speeds and allow yourself plenty of time to reach your destination. Our road crews and public safety officials thank you for your patience and cooperation.