Weather Outside Your Window: Vehicles buried in snow, highways shut down in Colorado during extreme avalanche conditions

By Brian Lada, AccuWeather meteorologist and staff writer

Colorado is facing potentially historic avalanches, threatening to shut down major highways that pass through the Rocky Mountains and forcing some popular ski resorts to close their slopes.

An avalanche was reported on Highway 91 near Copper Mountain, Colorado, on Thursday afternoon with reports of multiple vehicles buried in snow. No injuries were reported.

This is the latest in a string of avalanches across Colorado.

A car buried in snow following an avalanche on Highway 91 in Colorado. (Photo/CSPDistrict4)

On Thursday, the avalanche danger in Colorado was elevated to extreme, the highest on the scale established by the National Avalanche Center.

“This is the first time that four backcountry zones have gone to Extreme Avalanche Danger since the ten-zone forecast format began,” the Friends of the Colorado Avalanche Information Center (CAIC) said on Thursday morning.

"Historic avalanches have run around the region [Thursday] morning, and they will continue to do so," they added.

Even areas that are not typically prone to avalanches may be at risk due to the extreme danger, such as low-elevation avalanche terrain that rarely has slides.

“The state has already seen several historic slides. Be safe [and] avoid backcountry travel,” American Avalanche Association said.

The National Weather Service (NWS) has also issued avalanche warnings in some of the mountainous terrain across Colorado.

Intense snowfall and strong winds are two of the primary weather factors that prompted the unusually high avalanche risk, accord to the NWS warning.

The North American Public Avalanche Danger Scale (Image/National Avalanche Center)

Avalanche danger has been growing over the past several days with some avalanches disrupting travel along Interstate 70. This includes a slide that buried cars on the interstate on Sunday and forced the highway to be closed for several hours.

Some ski resorts across Colorado have closed some slopes due to the avalanche risk, including Breckenridge and Arapahoe Basin.

Skiers and snowboarders planning to head to Colorado ski resorts in the coming days should check with the resorts to see when the danger has diminished and when slopes will be re-opened.

Several avalanches were reported on Wednesday night and early Thursday morning across Colorado causing temporary road closures.

When avalanches occur, it can take road crews hours to clear the road of snow and debris, so traffic can safely pass through.

Despite the recent avalanche activity, no fatalities have been reported in Colorado this week, according to the American Avalanche Association.

People should continue to use caution when heading into the Colorado Rockies through the weekend as the elevated risk for avalanches will likely persist across the region.