Considerable avalanche danger will be encountered over a wide area
Edition: 5.12.2021, 17:00 / Next update: 6.12.2021, 18:00
Snowpack
During the last 8 days in the northern and the furthermost western regions there has been 150 to 200 cm of fresh snow registered over widespread areas, in the other regions 40 to 100 cm widespread. The fresh fallen snow and freshly generated snowdrift accumulations from this period were deposited on top of a thin, soft old snowpack with expansively metamorphosed (faceted) snow crystals. Thus, the snowpack layering is unfavourable above 2000 m on west-facing, north-facing and east-facing slopes in particular. Most of the avalanches which have released in the last few days fractured in this weak old snow.
In many places in the northern and the furthermost western regions there was a small amount of rainfall up to 1500 to 2000 m on Saturday.
Observed weather on Sunday, 05.12.2021
On Saturday evening the snowfall level descended down to low lying areas. On Saturday night the intensive snowfall came to an end, subsequently there were only isolated showers. During the course of the day on Sunday it turned quite sunny in the southern Upper Valais, in central Grisons and in the Upper Engadine; in the other regions of Switzerland skies remained overcast. In the furthermost southern regions it was dry and sunny during the day.
Fresh snow
Between Saturday afternoon and Sunday afternoon, the following amounts of fresh snow were registered above 2000 m:
  • western and central sectors of the northern flank of the Alps, northern and western parts of Lower Valais: 20 to 40 cm;
  • in the other regions of Switzerland, up to 20 cm over widespread areas; in the furthermost southern regions it was dry.
Thus, since Friday the following overall amounts of fresh snow have been registered above 2000 m:
  • northern flank of the Alps west of the Blüemlisalp, furthermost western part of Lower Valais: 60 to 80 cm, as much as 100 m along the French border;
  • remaining regions of the northern flank of the Alps and of northern Valais: 40 to 60 cm;
  • remaining parts of southern Valais, Grisons north of the Anterior Rhine: 20 to 40 cm; in the other regions, less.
About 40 cm of moist fresh snow was registered on the highest summits of the Jura region.
Temperature
At midday at 2000 m, between -9 °C in the northern regions and -6 °C in the southern regions.
Wind
  • During the nocturnal hours winds will be blowing at strong velocity in some places, from westerly to northwesterly directions;
  • during the daytime, winds will be blowing at light to moderate strength in the mountains.
Weather forecast through Monday, 06.12.2021
During the night, a few centimetres of snowfall is expected over widespread areas, falling down to low lying area. On Monday it will become increasingly sunny from the west, except on the northern flank of the Alps and in northern Grisons. In the southern regions it is expected to remain dry and the day will be sunny.
Fresh snow
  • On Sunday night, a few centimetres of fresh snow is anticipated over widespread areas;
  • in the southern regions and the Engadine it will remain dry.
Temperature
At midday at 2000 m, -9 °C in the northern regions and -6 °C in the southern regions.
Wind
Winds will be blowing at light to moderate strength from northerly directions, blowing from westerly directions in the Prealps.
Outlook through Wednesday, 08.12.2021
Tuesday
On Monday night, 5 to 10 cm of fresh snow falling down to low lying areas is anticipated over widespread areas. Starting at midday it will turn increasingly sunny from the west. In the southern regions it will be dry and the day will be quite sunny. The northwesterly winds will be blowing intermittently at moderate to strong velocity.
In the northern and the western regions, small snowdrift accumulations which will be prone to triggering are expected to form at high altitudes. Otherwise the avalanche danger levels will decrease on the northern flank of the Alps and in the furthermost western part of Lower Valais. In the other regions of Switzerland, avalanche danger levels are not expected to change significantly.
Wednesday
On Tuesday night precipitation will set in, and on Wednesday is expected to intensify during the course of the day. In the valleys of the north, foehn influence will still be felt in the early morning hours, elsewhere a temporarily strong-velocity southwesterly wind will be blowing.
In the western regions, avalanche danger levels are expected to increase. Also in the remaining regions of Switzerland, a slight increase in danger levels is possible.