In the west and in the south some new snow. Wet avalanches during the day
Edition: 25.4.2021, 17:00 / Next update: 26.4.2021, 18:00
Snowpack
The snow cover at elevated altitudes is becoming thoroughly wet to an increasing degree: on south-facing slopes below approximately 3000 m; on east-facing and west-facing slopes below approximately 2600 m; and on north-facing slopes below approximately 2200 m.
Nocturnal skies on Sunday night will be overcast in many places and a small amount of precipitation is expected from region to region. Thus, a melt-freeze crust will hardly be able to form. As a result of daytime warming the snowpack will rapidly lose its stability during the morning hours and the danger of wet-snow and gliding avalanches will increase. On north-facing slopes below approximately 2200 m, increasingly frequent wet-snow avalanches are possible as a result of rainfall and the ongoing progression of snowpack wetness.
In the last few days isolated wet-snow and gliding avalanches have been reported. Gliding avalanches can grow to large size in the regions where there has been heavy snowfall.
Observed weather on Sunday, 25.04.2021
It was predominantly sunny accompanied by cloudbanks in the eastern regions more than anywhere else. During the afternoon convective cloud build-up was registered in the Prealps in particular.
Fresh snow
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Temperature
At midday at 2000 m, between +6 °C in the western and the southern regions and +3 °C in the eastern regions.
Wind
  • Winds during the night were blowing at light to moderate strength from northwesterly directions;
  • during the daytime hours winds were generally light.
Weather forecast through Monday, 26.04.2021
In the western and southern regions skies will be predominantly overcast and a small amount of snowfall is anticipated above approximately 2000 m by midday. In the northern regions it will be partly sunny accompanied by cloudbanks.
Fresh snow
  • Valais, southern flank of the Alps, and Upper Engadine: 5 to 10 cm;
  • elsewhere, only a few centimetres, or else it will remain dry.
Temperature
At midday at 2000 m, between +5 °C in the western regions and +3 °C in the eastern regions.
Wind
  • Winds during the night will be blowing predominantly at light to moderate strength from southwesterly directions, slackening off during the course of the day;
  • along the Prealps, a moderate to strong velocity bise wind will prevail in the early part of the night, thereafter blowing at light to moderate strength.
Outlook through Wednesday, 28.04.2021
Tuesday
Skies will be heavily overcast in the southern regions, in the other regions of Switzerland variably cloudy. In the western and southern regions more than anywhere else precipitation is anticipated, falling as snow above approximately 1600 m in the southern regions, otherwise above approximately 2000 m. The danger of dry-snow avalanches is expected to increase slightly in the western and southern regions, elsewhere the danger levels are not expected to change significantly. The danger of wet-snow and gliding avalanches will remain at heightened levels in the regions where there was rainfall, elsewhere this danger will be subject to a slight daytime danger cycle.
Wednesday
Except in the eastern regions skies will be heavily overcast and a small amount of precipitation is anticipated over widespread areas. The snowfall level will lie at approximately 2000 m.
The danger of dry-snow avalanches is not expected to change significantly. The danger of wet-snow and gliding avalanches will remain at heightened levels.