As a consequence of warming and solar radiation a considerable danger of wet avalanches will be encountered over a wide area
Edition: 7.5.2022, 17:00 / Next update: 8.5.2022, 18:00
Snowpack
In areas below approximately 2200 m the precipitation during the last week fell predominantly as rain, in zones above 2800 m predominantly as snow. The various layers of fresh fallen snow and freshly generated snowdrifts of recent days were deposited atop one another there. These layers constitute the main danger for dry-snow avalanches.
During the night of predominantly overcast skies the snowpack surface below 2500 m is hardly able to freeze. As a consequence of solar radiation and the mild daytime temperatures, the snowpack surface swiftly softens and forfeits its stability. Increasingly frequent wet-snow avalanches are then possible.
On south-facing slopes the snowpack is thoroughly wet far up into high alpine regions; on west-facing and east-facing slopes the snowpack is wet below approximately 3000 m; and on north-facing slopes below approximately 2600 m. As a result of the zero-degree level ascending and the impact of solar radiation, the wetness of the snowpack on north-facing slopes at high altitudes continues to progress further.
Observed weather on Saturday, 07.05.2022
Nocturnal skies were predominantly overcast. From region to region there was a small amount of precipitation. The snowfall level lay between 2200 and 2500 m. During the daytime hours in the Valais and in the southern regions it was partly sunny, in the other regions of Switzerland skies were heavily overcast, but it tended to remain dry for the most part.
Fresh snow
Between Friday afternoon and Saturday afternoon in the high alpine regions in the southern Valais, 5 to 15 cm of fresh snow was registered. In the remaining regions of Switzerland there was less snowfall, or else it remained dry.
Temperature
At midday at 2000 m, between +6 °C in the Valais and in the southern regions, and +3 °C in the northern and the eastern regions.
Wind
Winds were blowing generally at light strength, at high altitudes intermittently at moderate strength, from easterly directions.
Weather forecast through Sunday, 08.05.2022
Nocturnal skies on Saturday night will initially be overcast, towards early morning in the northern regions they will become intermittently clear. Particularly in the southern Valais and in the Engadine, some precipitation is possible. The snowfall level will lie at approximately 2400 m. During the daytime hours it will be partly sunny to start with. During the afternoon, fresh convective cloud build-up is anticipated. Showers are possible.
Fresh snow
Between Saturday afternoon and Sunday afternoon, the following amounts of fresh snow are expected above 3000 m in the southern Valais: 5 to 10 cm. In the remaining regions of Switzerland it will remain predominantly dry.
Temperature
At midday at 2000 m, +6 °C, the zero-degree level will lie at 2800 m.
Wind
Winds will be predominantly light from easterly directions.
Outlook through Tuesday, 10.05.2022
Nocturnal skies on Sunday night will be predominantly clear, nighttime skies on Monday night will be clear. The snowpack surface will freeze particularly in zones above 2500 m and form a crust capable of bearing loads. During the daytime hours it will be mostly sunny on both days. Particularly on Monday, convective cloud build-up is anticipated during the course of the day, and showers are possible. The zero-degree level will ascend to 3300 m on Tuesday.
The danger of wet-snow avalanches is expected to increase on each day already during the morning hours. Backcountry tours and ascents to mountain refuges need to be brought to an end early in the day. The danger of dry-snow avalanches requires attentiveness in particular on very steep north-facing slopes in high alpine regions.