Avalanche Forecasts

Learn about the European Avalanche Danger Scale, snow stability, and what to look out for before going off-piste...

Snow stability is important: when the snow is stable it takes more than one person to trigger a release. When the snow is less stable, then just one person can trigger a slab. Plus there is more of a chance that the slab will release above you, making the consequences that much worse.

Avalanche forecasts tell you about snow stability: reading or listening to the avalanche forecast is essential to understand the risks for the day. It includes a danger rating. To use the avalanche forecast, you must understand the definition for the ratings. You also need to get an idea of where the instability is most acute on that particular day.

Danger level Snow stability Probability that an avalanche can be triggered
1
low
Very few unstable slabs. The snow pack is well bonded and stable in most places. Triggering is possible generally only with high additional loads on a very few very steep slopes. Only a few small natural avalanches (sluffs) possible.
2
moderate
Unstable slabs possible on some steep slopes. Triggering is possible with high additional loads, particularly on the steep slopes indicated in the bulletin. Large natural avalanches not likely.
3
considerable
Unstable slabs probable on some steep slopes. Triggering is possible, sometimes even with low additional loads. In certain conditions, medium and occasionally large sized natural avalanches may occur.
4
high
Unstable slabs likely on many steep slopes Triggering is probable even with low additional loads on many steep slopes. In some conditions, frequent medium or large sized natural avalanches are likely. Triggering and exposure to avalanches is possible on many lower angle slopes.
5
very high
The snowpack is weakly bonded and very unstable Numerous large natural avalanches are likely to reach low angle slopes. Extensive safety measures (closures and evacuation) are necessary. No off-piste or back country skiing or travel should be undertaken due to a high risk of exposure.

Terminology

  • High additional load: this would represent a group of skiers, a piste-machine or avalanche blasting equipment. A low additional load represents a single skier or walker
  • Steep slopes: those with an incline of more than 30 degrees
  • Steep extreme slopes: those which are particularly unfavourable in terms of their incline, terrain profile, proximity to ridges, and the smoothness of their underlying ground surface
  • Aspect: the direction the slope faces. If a skier has their back to the slope and is facing south, the aspect is south facing
  • Natural: without human assistance



  • Adapted from the European Avalanche Danger Scale by Henry's Avalanche Talk Val d'Isere Tel: 020 8144 5202 ¦ email All Modifications Copyright © Henry's Avalanche Talk