Considerable danger of dry and wet avalanches will be encountered over a wide area
Edition: 1.5.2021, 17:00 / Next update: 2.5.2021, 18:00
Snowpack
As a result of fresh snow and winds, snowdrift accumulations are increasing significantly at heightened altitudes.
Beneath the freshly generated drifts, the snowpack on east-facing, south-facing and west-facing slopes is thoroughly wet below approximately 3000 m. On north-facing slopes the snowpack between 2200 m and 2400 m became thoroughly moist for the first time during the last few days, and was thereby weakened. In particular in Grisons, where the snowpack evidences marked weak layers, even large-sized slab avalanches have been observed in this altitude band.
Observed weather on Saturday, 01.05.2021
During the night there were repeated bouts of precipitation, however also bright intervals in some places in the northern regions. During the morning hours in the furthermost eastern regions there were sunny spells. In the other regions of Switzerland skies were heavily overcast, accompanied by precipitation in the southern and western regions more than anywhere else. During the afternoon the precipitation extended increasingly to the other regions of Switzerland.
Fresh snow
The snowfall level in the northwestern regions lay at approximately 1700 m, in the other regions of Switzerland between 2000 and 2400 m. Between Friday afternoon and Saturday afternoon, the following amounts of fresh snow were registered:
  • central sector of the southern flank of the Alps: 20 to 40 cm;
  • elsewhere 5 to 15 cm over widespread areas; in northern Grisons and the Lower Engadine it remained dry.
Temperature
At midday at 2000 m in the northwestern regions at 0 °C, in the other regions of Switzerland at +3 °C.
Wind
  • During the nocturnal hours in the western regions, westerly winds were blowing temporarily at moderate strength;
  • in the other regions of Switzerland winds were blowing at light-to-moderate strength. During the daytime hours, strong-velocity southerly winds in some places.
Weather forecast through Sunday, 02.05.2021
In the early part of the night, intensive precipitation is anticipated over widespread areas. Subsequently the precipitation will come to an end in the southern regions. During the daytime in the Valais and in the southern regions, bright intervals are anticipated, in the northern and the eastern regions skies will remain heavily overcast accompanied by precipitation, although the intensity will slacken off significantly.
Fresh snow
The snowfall level will descend from approximately 2000 m down to 1000 to 1400 m in the northern regions and to approximately 1600 m in the southern regions. Between Saturday afternoon and Sunday afternoon, the following amounts of fresh snow are expected:
  • northern flank of the Alps, Ticino, Grisons: 20 to 40 cm;
  • Valais: 10 to 20 cm.
Temperature
At midday at 2000 m, between -2 °C in the northern regions and +2 °C in the southern regions.
Wind
  • Winds in the early part of the night will by southerly, then shift to northerly;
  • subsequently, winds will be blowing at moderate strength. To some extent, a strong-velocity northerly wind will be blowing in the southern regions and on the Main Alpine Ridge.
Outlook through Tuesday, 04.05.2021
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 recede somewhat. As a result of daytime warming and solar radiation the danger of wet-snow avalanches will increase during the course of the day.
Tuesday
Following a night of partially clear skies, it will be predominantly overcast during the daytime hours. In the afternoon a small amount of snowfall is anticipated above 1600 to 1800 m. Strong-velocity westerly winds are expected to arise.
The danger of dry-snow avalanches is not expected to change significantly. The danger of wet-snow avalanches will increase somewhat during the course of the day.