The avalanche risk factor scale only provides an overall assessment of the risk of avalanche occurring. An assessment must be made of every slope throughout the day taking into account, for example, previous snow pack layering, wind, temperature, steepness and orientation of the slope.
The degree of avalanche hazard depends on the stability of the snowpack and is an indication of the probability of avalanche. It indicates the likely effects on traffic, residential areas and on off-piste activities.
Slopes indicated in the avalanche bulletin are generally described in more detail (altitude, slope aspect, type of terrain, etc.).
1 low / gering / faible / debole
- Snowpack is generally well bonded and stable.
- Triggering is possible only with high additional loads on a few very steep extreme slopes. Only a few small natural avalanches (sluffs) possible.
- No hazard from avalanches.
- Virtually no restrictions on off-piste skiing & travel.
2 moderate / maessig / limite / moderato
- The snowpack is moderately well bonded on some steep slopes otherwise generally well bonded.
- Triggering is possible with high additional loads, particularly on the steep slopes indicated in the bulletin. Large natural avalanches not likely.
- Virtually no hazard from natural avalanches.
- Generally favourable conditions. Routes should still be selected with care, especially on steep slopes of the aspect and altitude indicated.
3 considerable / erheblich / marque / marcato
- The snowpack is moderately to weakly bonded on many steep slopes
- Triggering is possible, sometimes even with low additional loads. The bulletin may indicate many slopes that are particularly affected. In certain conditions, medium and occasionally large sized natural avalanches may occur.
- Traffic and individual buildings in hazardous areas are at risk in certain cases. Precautions should be taken in these areas.
- Only experienced persons able to evaluate avalanche hazard should carry out off-piste skiing and travel. Steep slopes of the aspect and altitude indicate should be avoided.
4 high / gross / fort / forte
- The snowpack is weakly bonded in most places.
- Triggering is probable even with low additional loads on many steep slopes. In some conditions, frequent medium or large sized natural avalanches are likely.
- Avalanches may be of large magnitude. In hazardous areas, closure of road and other transport is recommended in some circumstances.
- Off-piste and backcountry skiing and travel should be restricted to low-angled slopes; areas at the bottom of slopes may also be hazardous.
- The snowpack is generally weakly bonded and largely unstable.
- Numerous large natural avalanches are likely, even on moderately steep terrain.
- Extensive safety measures (closures and evacuation) are necessary.
- No off-piste or back country skiing or travel should be undertaken.
- Additional load:
- high: e.g. group of skiers, piste machine, avalanche blasting.
- low: e.g. single skier, walker.
- Steep slopes: Slopes with an incline greater than 30 degrees.
- Steep extreme slopes: Those which are particularly unfavourable in terms of the incline, terrain profile, proximity to ridge, smoothness of underlying ground surface.
- Aspect: Compass bearing directly down the slope.
- Natural: Without human assistance.
Last updated on 9th July 2018