A clear night will be followed in the early morning by favourable avalanche conditions mostly, but wet and gliding avalanches will occur later

Edition: 24.4.2021, 17:00 / Next update: 25.4.2021, 18:00

Snowpack

The snow cover at high 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. Particularly on very steep north-facing slopes, isolated dry-snow avalanches can still be triggered in the near-surface layers.
During the night of clear skies on Saturday night, a melt-freeze crust capable of bearing loads will be generated on east-facing, south-facing and west-facing slopes more than anywhere else. During the course of the morning hours, this crust will soften up swiftly. The danger of wet-snow and gliding avalanches then increases during the course of the morning. Over the last few days, isolated wet-snow and gliding avalanches have been reported. Gliding avalanches can grow to large size in the regions where snowfall has been heavy.

Observed weather on Saturday, 24.04.2021

It was sunny and mild, accompanied by cloudbanks in central Ticino and in Sotto Ceneri. During the afternoon, convective cloud build-up took place in the Prealps in particular.

Fresh snow

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 were blowing at light to moderate strength from westerly to northwesterly directions.

Weather forecast through Sunday, 25.04.2021

Nocturnal skies on Saturday night will be predominantly clear. During the daytime on Sunday it will be sunny for the most part, accompanied by cloudbanks in the western regions in particular during the course of the day.

Fresh snow

Temperature

At midday at 2000 m, between +6 °C in the western and southern regions and +3 °C in the eastern regions, with the zero-degree level at 2800 m in the west and south, and at 2500 m in the east.

Wind

Winds at high altitudes will be blowing at moderate strength from northwesterly directions, especially during the nighttime hours on Saturday night. During the course of the day on Sunday, the winds will slacken off;
in the Prealps, a weak-to-moderate strength bise will arise and intensify during the course of the day.

Outlook through Tuesday, 27.04.2021

Monday

In the western and the southern regions, skies are expected to be predominantly overcast. In the southern Valais and on the southern flank of the Alps a small amount of snowfall is anticipated above approximately 2000 m. In the northern regions it will be partly sunny accompanied by cloudbanks. At elevated altitudes a moderate velocity westerly-to-southwesterly wind will be blowing intermittently.
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 in the regions where there was rainfall, elsewhere this danger will flucturate in accord with a daily danger cycle.

Tuesday

In the southern regions it will be heavily overcast, in the other regions of Switzerland variably cloudy. Precipitation is expected in the western and southern regions more than anywhere else, falling as snow above approximately 1600 m in the southern regions, above approximately 2000 m in the other regions. The amounts of precipitation which can be expected are still uncertain.
It is currently assumed that the danger of dry-snow avalanches will increase in the western and the southern regions, elsewhere no significant change is anticipated. The danger of wet-snow and gliding avalanches will remain at heightened levels in the regions where there was rainfall, elsewhere this danger will fluctuate in accord with a slight daytime danger cycle.