EUROPEAN AVALANCHE DANGER
The European risk scale for the avalanches includes 5 levels defined by an assessment of the stability and its consequences in term of probability trigger avalanches. None of the risk indications is to disregard. In mountain, risk 0 doesn't exist and the danger whom skiers, snowboarders or pedestrian exposes itself, grows as well as the value of the indications. The avalanche risk is not a measurable parameter; every indication of the scale translates not what is going to happen, but what can happen with the best probability, considering the analysis of the situation and the knowledge. You can find the flags at the departure and the arrival of main ski lifts and news-bulletins are at different information points.
|European risk scale
||Stability of the mantle of snow
||Signification of flags
||Generally stable snow, so the conditions to practice the mountain sports are favorable. Isolated areas of instability like in strong declivity sectors or in crests and pass having slope ruptures. Trigger risk is not considered in must of cases but under the strong overcharge effect. Small avalanches or streams represent natural trigger.
||The general stability is satisfactory but localized instability affects some slopes whom the exhibition and the altitude are often mentioned. Trigger risk concerns only few slopes. Not very dangerous but under strong overcharge effects (a skiers group, for example). Spontaneous trigger risk is not very important. Streams or avalanches that can occur are, in must of case, small size.
||The instability worsens and involves a lot of slopes of which the topographic particularities are often described on the news-bulletin. According to the situations, most exposed areas could be mentioned but remember that the reality of the land, notably after blown snow episodes, excludes a strict localization of the sectors. The instability is marked enough and so trigger can occur just by small overcharge effect, as the passage of only one skier. When natural trigger is foreseen, this only means few avalanches, only some of them can be bigger. Somme material damages can happen remaining exceptional in this kind of situation.
||The instability affects most slopes, whose features can be signaled in the news bulletin. In many sectors concerned by this instability by weak overcharge (passage of only one skier for example). If the accidental trigger risk is always strong and preoccupying, it is not the same thing when we talk about trigger risk. Indeed the indication "4" described very different snow situations and the risk of spontaneous triggered avalanches can be strong or little marked or even very weak. These nuances are indicated in the news bulletin.
||The instability of the mantle of snow is very strong and generalized. Very active, cold and blown snowfall episodes, brutal warming up and rain affecting a transformed mantle of snow… numerous and thick avalanches can occur and can reach some gently sloping area (lower than 20°) Some situations covered by "5" risk presents a character of exceptional gravity. In human or material level, consequences can be very serious when big size avalanche occurs. Pylons, buildings and roads can be damaged. In preoccupying cases, special news bulletins are given out toward the regional and departmental services of security as well as toward the media ("avalanches" regional weather report alert, weather press release).