Wind slab
- Alle Höhenlagen
As a consequence of new snow and wind a high avalanche danger will be encountered in some regions.
The more recent wind slabs are in some cases prone to triggering. They are to be found in particular in gullies and bowls, and behind abrupt changes in the terrain. Avalanches can in some places be released by people and reach medium size. Avalanches can additionally in some places be released in deeper layers also. This applies in particular on west, north and east facing slopes. Backcountry touring calls for careful route selection.
Snowpack Over the course of this last week there was a lot of fresh snow registered over widespread areas in the northern regions. Most of the fresh fallen snow was registered on the northern Alpine Ridge and in northern Grisons. There, all in all, there was 50 to 80 cm of fresh snow, from the Grimsel Pass into the Glarus Alps as much as 100 cm. In these cited regions more than anywhere else, a huge amount of additional snowfall is still anticipated by Sunday afternoon, accompanied by strong-velocity northerly winds in some places. Furthermore, in the uppermost sections of the old snow cover bordering on melt-freeze crusts there are expansively metamorphosed (faceted) and weakened layers evident in some places. On west-facing, north-facing and east-facing slopes above approximately 2200 m more than anywhere else, there are weakened layers also evident in the lowermost part of the snowpack. In Grisons and in the southern part of the Valais more than anywhere else, these layers are blanketed over by only shallow fresher snow in some places and there, are prone to triggering to some extent. In the western part of the Lower Valais and on the northern flank of the Alps, the more deeply embedded layers inside the snow cover are frequently blanketed by thick layers and for that reason are currently unlikely to trigger. Observed weather review Saturday, 15.04.2023 Nighttime skies in the western regions were overcast, in the eastern and the southern regions skies were partly clear. In the western regions there was precipitation which fell already in the early part of the night and which subsequently spread into regions further to the east during the course of the day on Saturday. The snowfall level ascended from 1000 to nearly 1500 m. Fresh snow Between Friday evening and Saturday afternoon the following amounts of fresh snow were registered above approximately 2000 m:
Temperature At midday at 2000 m, between -2 °C in the northern regions and +2 °C in the southern regions. Wind Winds were blowing at light to moderate strength from northwesterly directions. Weather forecast through Sunday, 16.04.2023 Skies are expected to be heavily overcast and precipitation is anticipated over far-reaching areas. Precipitation is expected to be intensive on the northern Alpine Ridge. Only in the central sector of the southern flank of the Alps will it be dry and predominantly sunny. The snowfall level will lie at 1200 to 1500 m. Fresh snow Between Saturday afternoon and Sunday afternoon the following amounts of fresh snow are expected above approximately 1800 m:
Temperature At midday at 2000 m, between -2 °C in the northern regions and +1 °C in the southern regions. Wind Winds are expected to be northerly,
Outlook through Tuesday, 18.04.2023 Monday In the western and the southern regions, skies will be partly clear. Further to the east, a small amount of additional snowfall is still expected to fall above 1200 to 1400 m, and skies will remain overcast all day long. Winds will be blowing at light to moderate strength from northeasterly directions. The danger of dry-snow avalanches is expected to decrease in the western regions. In the remaining regions of Switzerland, avalanche danger levels are not expected to change significantly. In the northern and the eastern regions more than anywhere else, conditions for winter sports enthusiasts in backcountry terrain away from secured ski runs will remain critical. The danger of wet-snow avalanches is expected to increase during the course of the day in the western regions. Tuesday On Monday night, skies will be only partly clear and some showers are anticipated. During the daytime hours on Tuesday it will be quite sunny, accompanied by convective cloud built-up and scattered showers. It will be somewhat milder. The danger of dry-snow avalanches is expected to decrease. The danger of wet-snow avalanches will increase somewhat during the course of the day.
Bulletin data: WSL Institute for Snow and Avalanche Research SLF (CC BY 4.0)