Encountering a Snow Cornice: How to Stay Safe in the Mountains
Snow cornices are one of the most deceptive and dangerous features in mountaineering. These overhanging masses of snow and ice form on the leeward side of ridges due to wind deposition, creating a false sense of security for climbers and skiers. They may look solid, but cornices can break unpredictably, leading to falls, avalanches, and life-threatening situations.
Here’s how to identify, assess, and safely navigate snow cornices while mountaineering, backcountry skiing, or winter hiking.
What is a Snow Cornice?
A cornice is an overhanging windblown snow and ice formation that develops along ridgelines and mountain slopes. It forms when strong winds transport snow over the crest of a ridge, depositing layers on the downwind side. Over time, the buildup extends outward, creating a fragile ledge.
Why Are Cornices Dangerous?
They Look Solid but Aren’t – A cornice can extend far beyond the actual ridge, appearing like stable ground when it's actually unsupported snow.
They Can Collapse Without Warning – The weight of a person, shifting temperatures, or even a loud noise can trigger a break.
They Can Trigger Avalanches – When a cornice fractures, it may trigger an avalanche below, burying climbers or skiers in its path.
Limited Visibility – In poor weather or whiteout conditions, cornices are hard to see, increasing the risk of accidental entry.
They Can Collapse Without Warning – The weight of a person, shifting temperatures, or even a loud noise can trigger a break.
They Can Trigger Avalanches – When a cornice fractures, it may trigger an avalanche below, burying climbers or skiers in its path.
Limited Visibility – In poor weather or whiteout conditions, cornices are hard to see, increasing the risk of accidental entry.
Identifying Cornices in the Field
Before stepping onto a ridge or navigating snow-covered slopes, take time to assess the terrain for potential cornice hazards.
Signs of a Cornice Formation:
Overhanging Snow at the Edge of a Ridge – Appears like a snow "wave" or "lip" extending outward.
Cracks in the Snowpack – Fracture lines near ridgelines can indicate instability and possible cornice collapse.
Drifting Snow and Wind Deposits – Fresh windblown snow can create or weaken existing cornices.
Hollow-Sounding Snow – If tapping the surface produces a hollow sound, you may be standing on unsupported snow.
Cracks in the Snowpack – Fracture lines near ridgelines can indicate instability and possible cornice collapse.
Drifting Snow and Wind Deposits – Fresh windblown snow can create or weaken existing cornices.
Hollow-Sounding Snow – If tapping the surface produces a hollow sound, you may be standing on unsupported snow.
Pro Tip: If unsure about a cornice, stay well back from the edge and assess its depth and stability before proceeding.
The crack in the snow indicates a cornice
How to Avoid and Navigate Cornices
Route Selection: Minimize Exposure
Stay well away from ridgelines where cornices might overhang.
Look for safer ridges or lower-angle routes that avoid cornice-prone areas.
If uncertain, probe with a ski pole or ice axe to check for hollow snow.
Look for safer ridges or lower-angle routes that avoid cornice-prone areas.
If uncertain, probe with a ski pole or ice axe to check for hollow snow.
Recognizing a Safe Path
Move on the windward side of the ridge, not the leeward side where cornices form.
If crossing near a potential cornice, spread out to reduce weight pressure on one point.
Never blindly follow tracks—other climbers may have unknowingly walked onto a cornice.
If crossing near a potential cornice, spread out to reduce weight pressure on one point.
Never blindly follow tracks—other climbers may have unknowingly walked onto a cornice.
If You Must Cross a Cornice
Probe the snow before stepping forward to test stability.
Use ropes, ice axes, and crampons for added security.
If descending, avoid dropping onto steep lee slopes, as they may avalanche easily.
Consider using a belay system if moving onto potentially unstable terrain.
Use ropes, ice axes, and crampons for added security.
If descending, avoid dropping onto steep lee slopes, as they may avalanche easily.
Consider using a belay system if moving onto potentially unstable terrain.
The potential fracture zone is closer than you might think.
What to Do If a Cornice Breaks?
Even with caution, accidents happen. Here’s what to do in an emergency:
If You or Someone Falls
Self-Arrest Immediately – If sliding, use an ice axe to stop your fall.
Stay Calm and Communicate – If in a group, alert others and establish a rescue plan. Check for Injuries – If a climber is partially buried, assess for signs of trauma or hypothermia.
Stay Calm and Communicate – If in a group, alert others and establish a rescue plan. Check for Injuries – If a climber is partially buried, assess for signs of trauma or hypothermia.
If a Cornice Triggers an Avalanche
Yell to Alert Others – Warn your group if a break or avalanche occurs.
Deploy Avalanche Safety Gear – If caught in an avalanche, activate an airbag if you have one.
Swim to Stay on Top – Try to stay on the surface by swimming with upward strokes.
Deploy Avalanche Safety Gear – If caught in an avalanche, activate an airbag if you have one.
Swim to Stay on Top – Try to stay on the surface by swimming with upward strokes.
Create an Air Pocket – If buried, punch out a breathing space near your face.
Pro Tip: Always carry avalanche rescue equipment, including:
Avalanche Transceiver – Helps rescuers locate buried climbers.
Avalanche Probe – Assists in pinpointing a buried victim’s location.
Shovel – Essential for digging out trapped climbers.
Essential Gear for Cornice-Prone Terrain
Ice Axe & Crampons – For stability on icy ridges.
Ropes & Harnesses – For protection when crossing exposed terrain.
Avalanche Safety Gear – Beacon, probe, and shovel.
Helmet – Protects against falling ice and rock.
Ski Poles or Probe Pole – Helps test for hollow snow.
GPS & Map – Cornices can be hard to see in low visibility; know your route.
Ropes & Harnesses – For protection when crossing exposed terrain.
Avalanche Safety Gear – Beacon, probe, and shovel.
Helmet – Protects against falling ice and rock.
Ski Poles or Probe Pole – Helps test for hollow snow.
GPS & Map – Cornices can be hard to see in low visibility; know your route.
An example of what NOT to do...
Snow Stability & Weather Factors
Cornices are affected by weather conditions. Always check the avalanche forecast before heading into the mountains.
Unstable Cornices Are More Likely When:
Recent Heavy Snowfall – Fresh snow adds weight and stress.
Strong Winds – Wind transports snow, enlarging cornices.
Rapid Temperature Changes – Warming weakens the snow structure.
Prolonged Sun Exposure – Direct sunlight can cause cornices to soften and collapse.
Strong Winds – Wind transports snow, enlarging cornices.
Rapid Temperature Changes – Warming weakens the snow structure.
Prolonged Sun Exposure – Direct sunlight can cause cornices to soften and collapse.
Pro Tip: If the forecast warns of wind-loading, warming, or unstable conditions, reconsider your route or turn back.
When in Doubt, Hire a Guide
If you’re new to winter mountaineering or backcountry travel, consider hiring a certified mountain guide. They provide expert knowledge of safe routes and avalanche conditions, training in snow stability assessment, and hands-on experience in rope techniques and crevasse rescue.
Pro Tip: If you’re inexperienced, never travel alone in cornice-prone terrain.
Respect the Snow, Stay Safe
Snow cornices are beautiful yet deadly features in the mountains. Whether you’re climbing, skiing, or snowshoeing, respect the risks, assess the terrain, and always prioritize safety.
Stay smart, stay safe, and enjoy the mountains!
