Wind slab
- Above 2,400 m
As a consequence of new snow and stormy weather a considerable avalanche danger will be encountered in some regions.
Snowpack
As a consequence of the rain at the beginning of the week the snowpack became thoroughly wet below altitudes of approximately 2400 m. As a result of the lower temperatures, the old snowpack is now stabilising to an increasing degree. On Wednesday and on Thursday there was a small amount of snowfall which in general bonded well with the moist old snowpack surface at high altitudes. As a result of the fresh fallen snow and strong to storm-strength westerly to northwesterly winds, snowdrift accumulations are expected to be generated on Friday which will be prone to triggering. As a consequence of the large amounts of snowfall in the western and in the northern regions, these snowdrift accumulations could be large. In the regions south of the Main Alpine Ridge, on the other hand, there is no significant precipitation anticipated.
Weather forecast through Friday, 17.11.2023
On Thursday night, precipitation is expected to set in from the west. During the daytime hours on Friday skies will be heavily overcast and precipitation is anticipated over widespread areas. In central Ticino and southern Ticino it is expected to remain dry. As a consequence of northerly winds it will be quite sunny. The snowfall level on Thursday evening will lay at 2000 m, subsequently during the night the snowfall level will rapidly descend to 800 to 1000 m.
Fresh snow
Between Thursday evening and Friday afternoon the following amounts of fresh snow are expected above approximately 1800 m:
Temperature
Temperatures are expected to drop. At midday at 2000 m, to -4 °C in the northern regions, and to -2 °C in the southern regions.
Wind
Observed weather review Thursday, 16.11.2023
On Wednesday night, skies were partly clear. During the daytime hours on Thursday it was variably cloudy accompanied by showers in the western and the northern regions, and by bright intervals in the southern and the eastern regions. The snowfall level lay between 2000 m in the western regions and 1600 m in the eastern regions.
Fresh snow
Above 2200 m: in the furthermost western regions there was maximum 10 cm of fresh snow registered, in the northern regions only a few centimetres from place to place.
Temperature
At midday at 2000 m, between +3 °C in the western regions and 0 °C in the eastern regions.
Wind
Outlook through Sunday, 19.11.2023
During the course of Friday night the precipitation will come to an end. In the northern and the eastern regions, as much as 20 cm of fresh snow is anticipated above 1200 m. During the daytime hours on Saturday it will be sunny to begin with, subsequently skies will become increasingly overcast from the west during the course of the day. On Sunday in the western regions it will be sunny to start with, in the remaining regions of Switzerland predominantly overcast, and a small amount of precipitation is expected. The snowfall level will ascend during Saturday night to 2700 m, subsequently descend to 2200 m during the course of the day on Sunday. The northwesterly winds will be blowing at moderate to strong velocity at high altitudes and also in the southern regions. On both days it is expected to be predominantly sunny in the southern regions. Avalanche danger levels are expected to decrease in the western regions more than anywhere else, in the other regions avalanche danger will not change significantly. As a consequence of solar radiation or else as a result of rainfall, moist loose-snow avalanches can be expected to trigger from the fresh fallen snow. Also gliding avalanches can be expected.
Bulletin data: WSL Institute for Snow and Avalanche Research SLF (CC BY 4.0)