Storm-strength foehn wind depositing new snowdrifts atop weak old snowpack
Fresh, trigger-sensitive snowdrift accumulations blanket marked weak layers in the old snow: activities in backcountry demand cautious evaluation of the terrain and the dangers, as well as restraint. Caution is imperative in ridgeline zones, as well as in wind-loaded gullies and bowls. Avalanches which release can fracture to deeper layers in the old snowpack and grow to medium size. Such danger zones occur especially on steep shady slopes and are impossible to spot. Also remote triggerings are possible. Whumpf noises and fractures when treading on the surface are alarm signals. On sunny slopes, generally small loose-snow avalanches can trigger naturally during the course of the day. In addition, trigger-sensitive snowdrift accumulations will be generated during the day in foehn-exposed regions.
Snowpack
Fresh snowdrift accumulations lie deposited atop loosely packed snow or surface hoar in many places above the treeline, and also on top of a weak old snowpack surface, particularly on steep shady slopes. Avalanches triggered by winter sports enthusiasts and fractures on the surface confirm how prone to triggering the snowpack is.
Tendency
Weak layers in the old snow can still be triggered by one single winter sports enthusiast. The likelihood of fresh drifts triggering will decrease during the course of the day only very little over the next period of time.
Danger level
1800m
Avalanche Problem
Persistent weak layer
1800m
Wind slab
Treeline
Avoid freshly generated snowdrift accumulations!
Stormy-strength foehn winds are generating fresh, trigger-sensitive snowdrift accumulations. A single winter sports enthusiast can trigger small slab avalanches in some places. If releases then sweep away deeper weak layers of the snowpack, the avalanche can in isolated cases grow to medium size. Caution is urged in ridgeline terrain, wind-loaded gullies and bowls. Danger zones are difficult to spot, they occur particularly in transitions from shallow to deep snow, for example, at entry points into gullies and bowls. Apart from the risks of being buried in snow masses, the danger of being swept along and forced to take a fall require caution. On sunny slopes, generally small loose-snow avalanches can trigger naturally during the course of the day.
Snowpack
Older snowdrift accumulations from last week often lie deposited atop loose old snow at high altitudes, or atop a melt-freeze encrusted old snowpack surface. Particularly on steep shady slopes, there are often unfavorable intermediate and fundament layers inside the old snowpack which have persisted.
Tendency
As a result of strong-to-stormy SW winds, fresh snowdrift accumulations will be generated. Thus, avalanche danger can increase again at high altitudes.
Danger level
treeline
Avalanche Problem
Wind slab
Treeline
Persistent weak layer
1400m
Avoid freshly generated snowdrifts!
Avalanche risk above the timberline is moderate, below that altitude it is low. Main problem: fresh snowdrifts. Small slab avalanches can be triggered in some places even by minimum additional loading. Danger zones occur in steep ridgeline terrain in N/NW/SE aspects and in wind-loaded gullies and bowls. Avalanches can in isolated cases sweep away deeper weak layers of the snowpack, but still remain small-sized.
Snowpack
Particularly on steep shady slopes, unfavorable intermediate layers inside the old snowpack have often persisted. During recent nights, surface hoar has often been generated. The melt-freeze crust which formed overnight softens up on sunny slopes during daytime hours. At lower altitudes there is little snow on the ground. South-facing slopes are increasingly becoming bare of snow.
