Wind slab
- Above treeline
- Size
- 2
Stability: poor · Frequency: some
Medium-sized avalanches possible
Stability: poor · Frequency: some
Stability: very poor · Frequency: few
Medium-sized avalanches possible
Avalanche danger above the timberline is moderate, below that altitude avalanche danger is low. Main problem: snowdrifts. They can be triggered as medium-sized slab avalanches even by one sole person engaged in winter sports. Avalanche prone locations are located in steep ridgeline terrain in NW-E-SE aspects as well as in wind-loaded gullies and bowls. In some places, avalanche prone locations are also found in steep forest aisles at lower altitudes. Frequency and size of danger zones increase with ascending altitude. At high altitudes, avalanches can in isolated cases fracture down to weak layers embedded in the old snow. Isolated medium-sized glide-snow avalanches can in addition trigger naturally on smooth grass-covered slopes in all aspects.
On the shady side, new snow and snowdrifts are deposited atop an unfavorable old snowpack surface consisting of expansively metamorphosed crystals, or -- in particular at lower altitudes -- surface hoar. Weak layers can also be embedded in the snowdrifts and are prone to triggering. In many places snowdrifts are blanketed by loose snow; difficult to recognize. Due to solar radiation the loose snow looses its firmness. In shady high altitude terrain there are locally weak layers embedded in the old snowpack consisting of graupel or faceted (expansively metamorphosed) crystals. In isolated cases such weak layers are still prone to triggering. The snowpack base is moist down to the ground, thus enabling gliding movements.
Increasing danger of wet avalanches as a result of rainfall up to higher altitudes.
Bulletin data: Avalanche Warning Service Bavaria (CC BY 4.0)