Snowpack

As a result of fresh snow and winds, snowdrift accumulations are being generated anew at high altitudes.
As a consequence of cloud cover and precipitation, the moist snowpack surface below approximately 2400 m is hardly able to re-gain its firmness during the nocturnal hours.
The snow cover is thoroughly wet below approximately 3000 m on south-facing slopes, below approximately 2800 m on east-facing and west-facing slopes. On north-facing slopes the progressive moistening of the snowpack between 2200 and 2400 m continues apace. Weak layers deeply embedded in the snowpack on north-facing slopes are becoming moist for the first time, and thereby, additionally weakened.

Observed weather on Friday, 30.04.2021

In the southern regions, intensive precipitation was registered during the early part of the night. Otherwise skies were predominantly clear in the Valais, partly clear in the other regions of Switzerland on Thursday night. During the daytime on Friday it was partly sunny in the northern regions. In the southern regions there were showers registered (and during the afternoon also in the north). The snowfall level lay between 1800 and 2000 m.

Fresh snow

Between Thursday afternoon and Friday afternoon:

Main Alpine Ridge from Bedretto as far as Bernina Pass and southwards therefrom: 10 to 20 cm;
in the other regions of Switzerland over widespread areas: 5 to 10 cm.

Temperature

At midday at 2000 m, approximately +4 °C in the northern regions and +2 °C in the southern regions.

Wind

Winds were southerly,

during the nighttime hours blowing predominantly at light strength;
during the daytime hours blowing at moderate to strong velocity.

Weather forecast through Saturday, 01.05.2021

Skies are expected to be predominantly overcast. Precipitation is anticipated over widespread areas which will be intensive particularly in the southern regions. The snowfall level will lie between 2200 m in the northern regions and 2400 m in the southern regions.

Fresh snow

Between Friday afternoon and Saturday afternoon:

Main Alpine Ridge from Great St. Bernard to the Rheinwald region and southwards therefrom, Aletsch region: 15 to 30 cm; as much as 40 cm in the central sector of the southern flank of the Alps;
in the other regions of Switzerland over widespread areas: 5 to 15 cm.

Temperature

At midday at 2000 m, between +2 °C in the northwestern regions and +5 °C in the furthermost eastern regions.

Wind

During the night winds will be blowing at light to moderate strength, during the daytime intermittently at strong velocity at high altitudes, from southerly directions.

Outlook through Monday, 03.05.2021

Sunday

In the early part of the night, intensive precipitation is anticipated over widespread areas. Subsequently as northerly winds arise, the precipitation will come to an end in the southern regions. In the remaining regions of Switzerland the precipitation will continue. The snowfall level will rapidly descend to approximately 1200 m in the northern regions, to 1600 m in the southern regions. During the daytime it will be quite sunny in the southern regions. On the northern flank of the Alps and in Grisons, approximately 20 to 40 cm of fresh snow is expected. However, these prognosticated amounts of fresh snow are uncertain.
The danger of dry-snow avalanches will increase over widespread areas, particularly at heightened altitudes. Wet-snow and gliding avalanches continue to be possible.

Monday

On Sunday night the precipitation will come to an end from the west. During the daytime on Monday it will be quite sunny.
The danger of dry-snow avalanches is expected to decrease somewhat. As a result of daytime warming and solar radiation, the danger of wet-snow avalanches will increase during the course of the day. Gliding avalanches continue to be possible.