Moderate avalanche danger will be encountered over a wide area. Wind slabs and weakly bonded old snow require caution
Edition: 25.12.2021, 17:00 / Next update: 26.12.2021, 18:00
Snowpack
In the lower part of the snowpack, particularly on west-facing, north-facing and east-facing slopes above approximately 2200 to 2400 m, as well as on south-facing slopes above approximately 2800 m, there are weak layers evident. These can be triggered by persons in some places, more than anywhere else in central Valais over the Ticino as far as Grisons. In the furthermost western part of Lower Valais and on the northern flank of the Alps these weak layers are covered over by thick layers of fresher snow so that they can hardly be triggered by persons.
On west-facing, north-facing and east-facing slopes more than anywhere else, the fresh fallen snow and freshly generated snowdrifts are being deposited on top of a weak old snowpack surface composed of expansively metamorphosed (faceted) snow crystals or surface hoar. On south-facing slopes the snowpack surface manifests pronounced effects from the sun, which makes it more favourable.
As a consequence of higher temperatures, increasingly frequent small-sized gliding avalanches have released at intermediate altitudes during the last two days.
Observed weather on Saturday, 25.12.2021
During the nocturnal hours of Christmas Day in the northeastern regions, a small amount of snowfall was registered above approximately 1800 m. During the daytime on Christmas Day skies were heavily overcast, but for the most part it remained dry.
Fresh snow
In the eastern sector of the northern flank of the Alps above approximately 1800 m, there was a few centimetres of fresh snow registered.
Temperature
At midday at 2000 m, 0 °C.
Wind
Winds were westerly, blowing at light to moderate strength.
Weather forecast through Sunday, 26.12.2021
Skies are expected to be heavily overcast. In the northern and the western regions, light precipitation will set in from the west during the nighttime hours of Christmas Day. The precipitation is expected to persist during the daytime on Boxing Day. The snowfall level will descend from approximately 1600 m down to 1300 m.
Fresh snow
By Sunday evening, the following amounts of fresh snow are anticipated at high altitudes:
  • northern flank of the Alps, Lower Valais and the highest summits of the Jura region: 5 to 10 cm;
  • in the other regions of Switzerland, less; in southern regions it is expected to remain dry.
Temperature
At midday at 2000 m, -1 °C.
Wind
Winds will be blowing at light to moderate strength, at the heights of the Jura region at moderate strength, from westerly directions.
Outlook through Tuesday, 28.12.2021
Monday
On Monday morning in the eastern regions, bright intervals are anticipated. In the other regions of Switzerland skies will be heavily overcast. Above approximately 1400 m in the northern and western regions, approximately 5 to 10 cm of fresh snow is anticipated, in the other regions less. The westerly winds will be blowing at light to moderate strength, in some places in the western regions at strong velocity during the afternoon.
In the northern and the western regions, avalanche danger levels are expected to increase. In Grisons and in the south, avalanche danger is not expected to change significantly.
Tuesday
On Tuesday skies will be heavily overcast, accompanied by precipitation. The snowfall level will ascend to approximately 1800 m. Most of the precipitation will fall in the western and northern regions, but the expected amounts are not yet certain. The westerly winds will intensify and be blowing at strong to storm strength during the afternoon. In the furthermost south it will be dry and quite sunny.
Avalanche danger levels are expected to increase over widespread areas, except in the furthermost southern regions. In the western and northern regions, Danger Level 3 (“considerable”) will presumably be reached.