Since Thanksgiving, numerous avalanches have been reported across popular backcountry areas in Colorado, including Loveland Pass, Berthoud Pass, and Bald Mountain near Breckenridge. Colorado avalanche officials warn that conditions are evolving into a challenging and unpredictable persistent slab problem.
Following a snowstorm that brought over 2 feet of snow to parts of the Colorado Rockies before Thanksgiving, the Colorado Avalanche Information Center (CAIC) issued a special avalanche advisory. Although the advisory was lifted on December 1, the avalanche danger remains moderate to considerable statewide, particularly in the northern mountains.
“You can trigger deadly avalanches nearly anywhere in the region,” officials stated in their December 2 forecast. Observers have documented nearly 20 avalanches in the Vail and Summit County region and over 15 along the Front Range since Thanksgiving.
On November 30, backcountry skiers triggered a small avalanche on Loveland Pass on an east-facing slope near the treeline. Despite no visible signs of instability, the slope gave way, highlighting the unpredictable nature of avalanche conditions. Officials caution that avalanches will become harder to trigger but also more difficult to anticipate as time passes since the storm.
Persistent slab avalanches are especially concerning, as they account for about two-thirds of avalanche fatalities in Colorado. These occur when a weak snow layer is buried beneath additional snow, creating a setup that can result in dangerous slides days, weeks, or even months later.
In regions like the Flat Tops, Front Range, and eastern Summit County, basal weak layers are a primary concern. If a slide triggers these deeper layers, it can propagate into a larger and more destructive avalanche.
The issue stems from early-season storms in October and November, which left behind weak, faceted snow on shaded slopes. Northerly and easterly aspects, where this snow was preserved, are now the most hazardous.
Recent snowfall has connected terrain, allowing avalanches to span entire bowls and wrap around features. Reports also indicate slides triggered from a distance and below the slopes.
Additionally, wind slab avalanches, created by snow drifting into compacted slabs, have been reported in northern mountain areas. These conditions further complicate backcountry travel.
To minimize risk, the CAIC advises backcountry travelers to stay on slopes under 30 degrees and avoid wind-exposed areas. While avalanche danger may decrease slightly to moderate in some regions, the persistent slab problem will remain a significant hazard.
“The bottom line is that you need to keep making conservative decisions,” officials emphasized. “Avoid traveling beneath overhead hazards and be extra cautious about the slopes you choose.”