Extraordinarily dangerous avalanche conditions.
Extreme is the highest of five levels on the avalanche danger scale and denotes extraordinarily dangerous avalanche conditions. Natural and human-triggered avalanches are certain; very large avalanches are expected in many areas; and all avalanche terrain should be avoided.
Extreme avalanche danger is used rarely in avalanche forecasts. It is employed when the likelihood and size of avalanches could present conditions that are outside the realm of many people’s experience. Conditions such as avalanches running beyond the existing bounds of their path, avalanches running into forested terrain, avalanches destroying structures, or avalanches running across valleys and up the other side are all possibilities under Extreme danger.