Persistent weak layers
- Above 2,200 m
Caution: small snowdrifts
Caution: small snowdrifts
As a result of intensifying winds, small-sized freshly generated snowdrift accumulations can be triggered as small-to-medium sized slab avalanches. Danger zones occur primarily behind steep drops in the terrain and in wind-loaded gullies and bowls. Frequency and spread of avalanche prone locations increase with ascending altitude. Furthermore, avalanches can fracture in weak layers of the old snow from large additional loading and in isolated cases then grow to medium size. Such isolated avalanche prone locations occur in spots where the snow is shallow or in transitions from shallow to deep snow. As a result of strong solar radiation, small wet loose-snow avalanches can trigger in extremely steep terrain.
Fresh snowdrifts which will be generated during the course of the day on Wednesday will be deposited on top of an unfavorable old snowpack surrace. No further releases have been reported from the somewhat older snow triggering. On steep south-facing slopes there is often a melt-freeze crust capable of bearing loads which then softens up during daytime hours. The mid-level part of the snowpack consists of well-settled, compact layers widespread which on high-altitude shady slopes cover a poorly structured old snowpack fundament.
Following the sunshine until past midday, cloud cover will move in during the afternoon from the west. In late afternoon, a striking cold front will move in, with storm-strength gusts and plummeting temperatures. Temperature at 2000m: dropping from +1 to -7 degrees; at 3000m: from -4 to -14 degrees. Initially moderate-strength SW winds, in afternoon strong-to-storm strength westerly to northwesterly winds at high altitudes.
A marked cold front will bring fresh snowfall and wind. Avalanche danger will increase.
Bulletin data: Avalanche Warning Service Vorarlberg (CC BY 4.0)