Avalanche Safety - Avalanche Risk Scale

Avalanche Risk Scale

Five Levels of Avalanche Risk

Ski resorts issue notices (bulletins) stating the level of Avalanche Risk every day.

The risk level is quoted from a five-point scale of increasing risk (of avalanche).

Before you ski or snowboard off-piste it is essential that you understand the Avalanche Risk Level for the local area and plan your skiing accordingly.

Note the absence of a Level Zero - there is NEVER zero risk of avalanche when there is snow on the mountain.

"Skier" in the text below indicates anyone on the snow - skier, snowboarder, climber or walker. Avalanches don't care.

Avalanche Risk Level		Snowpack Stability	Avalanche probability
1	Low Risk	Generally well bonded and stable.	Triggering is possible by groups of skiers on a few very steep extreme slopes. Small natural avalanches (sluffs) are possible.
2	Moderate	Less well bonded on some steep slopes, otherwise generally well bonded.	Triggering is possible by groups of skiers, particularly on steep slopes. Large natural avalanches may occur but are not likely.
3	Considerable	Moderately to weakly bonded on many steep slopes.	Triggering is possible, even by individual skiers. The bulletin may indicate many slopes which are particularly affected. Medium and occasionally large natural avalanches may occur.
4	High	Weakly bonded in most places.	Triggering is likely, even with single skiers, on many steep slopes. Frequent medium or large sized avalanches are likely.
5	Very High (Extreme)	Weakly bonded and largely unstable.	Numerous large natural avalanches are likely, even on moderately steep terrain.

The What, Where and What to do

The following are taken from the U.S. Avalanche Danger Descriptors and give a useful summary of each level - and how you should adapt your off-piste route planning accordingly.

Danger Level		Avalanche Probability and Avalanche Trigger	Degree and Distribution of Avalanche Danger	Recommended Action in the back country
WHAT		WHY	WHERE	WHAT TO DO
1	Low Risk	Natural avalanches very unlikely. Skier-triggered avalanches unlikely.	Generally stable snow. Isolated areas of instability.	Travel is generally safe. Normal caution advised.
2	Moderate	Natural avalanches unlikely. Skier-triggered avalanches possible.	Unstable slabs possible on steep terrain.	Use caution in steeper terrain on certain aspects (defined in accompanying statement).
3	Considerable	Natural avalanches possible. Skier-triggered avalanches probable.	Unstable slabs probable on steep terrain.	Be increasingly cautious in steeper terrain.
4	High	Natural and human triggered avalanches likely.	Unstable slabs likely on a variety of aspects and slope angles.	Travel in avalanche terrain is not recommended. Safest travel on windward ridges of lower angle slopes without steeper terrain above.
5	Very High (Extreme)	Widespread natural or human triggered avalanches certain.	Extremely unstable slabs certain on most aspects and slope angles. Large destructive avalanches possible.	Travel in avalanche terrain should be avoided and travel confined to low angle terrain well away from avalanche path run-outs.