| What it is | Mass of snow sliding down a slope |
| Most dangerous type | Slab avalanche |
| Key terrain | Steep slopes (~30–45°) |
| Manage with | Training, forecast, gear, terrain choice |
An avalanche is a rapid flow of snow down a slope, ranging from small sloughs to massive, destructive slides. The most dangerous type for backcountry travelers is the slab avalanche, where a cohesive slab of snow breaks free over a weak layer. Avalanches are the primary hazard of winter backcountry travel, and managing the risk requires education, the avalanche forecast, rescue gear, and conservative terrain choices.
This is general educational information, not avalanche training. Take a certified avalanche course (e.g., AIARE) and check your local forecast before entering avalanche terrain.
The core hazard
The deadliest form is the slab avalanche, born of weak layers in the snowpack; carry an avalanche beacon and know avalanche rescue.
Frequently asked questions
What is an avalanche?
An avalanche is a mass of snow that slides rapidly down a slope. They range from small loose-snow sloughs to large slab avalanches in which an entire cohesive layer of snow fractures and releases at once. Slab avalanches cause most avalanche fatalities because they can break above a traveler and bury them under tons of snow.
What causes avalanches?
Most dangerous avalanches happen when a cohesive slab of snow sits on top of a weaker layer within the snowpack and that weak layer fails — often triggered by the weight of a person. Key ingredients are a slab, a weak layer, a steep enough slope (commonly 30–45°), and a trigger. New snow, wind loading, rapid warming, and rain all increase danger.
How do you stay safe from avalanches?
Get formal avalanche education, check the local avalanche forecast before every trip, carry and know how to use a beacon, shovel, and probe (an airbag is recommended), travel with prepared partners, expose only one person at a time to hazard, and choose terrain conservatively. This is an overview — proper training is essential.
Sources
- Avalanche basics — Avalanche.org
- Avalanche education — American Institute for Avalanche Research and Education
- Avalanche encyclopedia — American Avalanche Association