At high altitudes slab avalanches can grow to large size.
Avalanche danger above the treeline is considerable, below that altitude avalanche danger is low. The main problem: fresh and older snowdrifts. In some places, slab avalanches can be triggered even by minimum additional loading; at high altitudes, isolated slabs can be large. Avalanche prone locations are found adjacent to and distant from ridges in steep terrain in NW/W/S aspects as well as in wind-loaded gullies and bowls. At high altitudes, avalanches can fracture down to weak layers embedded in the old snow. Where precipitation is heaviest, in addition small to medium-sized loose snow avalanches can trigger naturally in extremely steep terrain.
Snowpack
Due to strong westerly winds and the onset of snowfall the snow will be transported. Intermediate layers that are prone to triggering can be embedded in the fresh snowdrift accumulations. In leeward areas the old snowpack is in many places superficially moist and homogenous. Here and there, large faceted crystals have formed underneath near-surface melt-freeze crusts. More deeply embedded in the snowpack there are also soft expansively metamorphosed layers close to crusts at high altitudes.
Tendency
Rising avalanche danger due to continuing snowfall and wind.
Danger level
treeline
Avalanche Problem
Wind slab
Treeline
Ten to maximally 20 centimeters of new snow accompanied by wind
Avalanche danger above the treeline is moderate, below that altitude avalanche danger is low. Main problem: snowdrifts. In some places, slab avalanches can be triggered even by minimum additional loading and can be medium-sized. Avalanche prone locations are found adjacent to and distant from ridges in steep terrain in NW/W/S aspects as well as in wind-loaded gullies and bowls. At high altitudes, avalanches can fracture down to weak layers embedded in the old snow.
Snowpack
Due to strong westerly winds and the onset of snowfall the snow will be transported. Intermediate layers that are prone to triggering can be embedded in the fresh snowdrift accumulations. In leeward areas the old snowpack is in many places superficially moist and homogenous. Here and there, large faceted crystals have formed underneath near-surface melt-freeze crusts. More deeply embedded in the snowpack there are also soft expansively metamorphosed layers close to crusts at high altitudes.
Tendency
Due to strong westerly winds and the onset of snowfall the snow will be transported. Intermediate layers that are prone to triggering can be embedded in the fresh snowdrift accumulations. In leeward areas the old snowpack is in many places superficially moist and homogenous. Here and there, large faceted crystals have formed underneath near-surface melt-freeze crusts. More deeply embedded in the snowpack there are also soft expansively metamorphosed layers close to crusts at high altitudes.
