Bregenzerwald Mountains

Still trigger-sensitive intermediate layers on high-altitude shady slopes

Still trigger-sensitive intermediate layers on high-altitude shady slopes

On high-altitude shady slopes there are trigger-sensitive intermediate layers in the snowpack. Danger zones occur on shady wind-loaded steep slopes, behind abrupt discontinuities in the terrain and in gullies and bowls. Small-to-medium, in isolated cases large-sized slab avalanches can be triggered by the weight of one single person. Whumpf noises and glide-cracks are signals of imminent danger. Also remote triggerings are possible. Activities in backcountry demand a great deal of experience in assessing dangers on-site. Furthermore, on steep seldom-tracked shady slopes at high altitudes there are weak layers deeply embedded in the snowpack which are triggerable by large additional loading. Below 2200 m on sunny steep slopes, glide-snow avalanches are possible.

Fresh snow and drifts were able to settle at low and intermediate altitudes, and consolidate. With ascending altitude this process requires longer. Fresh snow and snowdrifts often lie deposited atop unfavourable old snowpack surfaces consisting of surface hoar, melt-freeze encrusted or softened layers. Bonding of fresh snow and drifts to these layers and also inside the snowpack itself is frequently poor. At high altitudes on steep shady slopes there are still older unfavourable intermediate layers inside the snowpack which are not visible to the naked eye. Naturally triggered avalanches confirm the proneness to triggering of the snowpack.

Nocturnal hours: a night of clear and cold skies, temperatures dropping to -4 to -10 degreers, in places to -15 degrees. Thursday: high-pressure front conditions, cloudless skies, brilliant sunshine. Slight SE foehn wind can be bothersome especially in Silvretta-Arlberg regions. At 2000 m: -10 to -7 degrees. Moderate easterly winds.

Mostly sunny in coming days due to high-pressure front conditions. Temperatures will remain wintery. The snowpack is still prone to triggering.