Mount Rainier National Park has issued a cornice danger warning amid multiple fatal avalanche accidents across the west. Known for its deep snowpack, “winter” conditions on Mount Rainier can last well into June or July with snow-covered trails at higher elevations. Many types of snow hazards exist inside the park including snow bridge, tree wells, and snow cornices. Here’s what Mount Rainier had to say about snow cornice dangers in a social media post from yesterday:
Mount Rainier National Park
Snow Cornices – Are you on safe footing?
A snow cornice is an overhanging edge of snow that develops on the downwind side of ridges and summits. Cornices are difficult to identify from the top of a ridgeline as it may appear that the ground continues underneath although the snow is just built up on itself. Travel cautiously on ridgelines, staying well away from cornices and unknown edges. As stated by the National Avalanche Center “Even a small cornice can be deadly if it carries you over a cliff or rocky terrain below.” Limit exposure on slopes below cornices to avoid being caught in a cornice-triggered avalanche.
National Avalanche Center
Cornice fall avalanche
An overhanging mass of wind-deposited snow that breaks off of a ridgeline and tumbles down the slope.
Credit: Utah Avalanche Center
Cornices typically form on the leeward side of a sharp, wind-exposed terrain break such as a ridge crest or summit. Cornice falls can trigger additional slab avalanches on the slope below, or they can simply consist of the cornice and any additional snow entrained by the cornice blocks. Accidents typically involve cornices breaking unexpectedly below ridgeline travelers, or occasionally from natural cornice falls that overtake travelers on slopes below.
Aerial view of a cornice fall that swept several climbers down a steep chute. Credit: Colorado Avalanche Information Center
A cornice fall that triggered a narrow slab avalanche. Credit: Crested Butte Avalanche Center
