Moderate danger of wet avalanches will be encountered over a wide area
Edition: 2.4.2021, 17:00 / Next update: 3.4.2021, 18:00
Snowpack
The snowpack became thoroughly wet over the course of this last week: on south-facing slopes below approximately 3200 m, on east-facing slopes below approximately 2500 m, on west-facing slopes below approximately 2800 m, and on north-facing slopes below approximately 1700 m.
In the uppermost third of the snow cover in many regions there is a marked weak layer evident. This layer is found most often in the vicinity of the layers of dust blown north from the Sahara desert to the Alps in February. During the course of this week, isolated wet-snow avalanches were triggered in this layer by persons. This also occurred during the hours before noon.
In the Valais and in the southern regions more than anywhere else, a melt-freeze crust capable of bearing loads will form on east-facing, south-facing and west-facing slopes during the nocturnal hours on Friday night. In the northern and eastern regions the nighttime hours will have reduced outgoing longwave radiation. As a result of the daytime warming and solar radiation, wet-snow avalanches are possible, in some places also large-sized ones.
On high-altitude north-facing slopes, isolated dry-snow avalanches can still be triggered.
Observed weather on Friday, 02.04.2021
Nighttime skies on Thursday night in the northern and the eastern regions were predominantly overcast and in the east there was some precipitation in the form of showers. The snowfall level lay at 2300 m. During the daytime on Good Friday it was predominantly sunny, in the eastern regions the residual clouds dispersed during the course of the morning hours. In the afternoon, convective cloud build-up was registered.
Fresh snow
Above approximately 2400 m:
Eastern sector of the northern flank of the Alps, northern Grisons, northern Lower Engadine: 5 cm from place to place;
Temperature
At midday at 2000 m, between +7 °C in the western and the southern regions and +4 °C in the eastern regions.
Wind
Winds were blowing at light to moderate strength from northerly directions.
Weather forecast through Saturday, 03.04.2021
Nocturnal skies on Friday night in the northern and the eastern regions will be predominantly overcast. In the early part of the night, a small amount of precipitation is anticipated. The snowfall level will descend from 2200 m down to approximately 1600 m. During the daytime on Holy Saturday skies in these regions will be overcast to begin with, subsequently after the residual clouds disperse it will become increasingly sunny.
In the Valais and in the southern regions, nighttime skies on Friday will be predominantly clear. On Holy Saturday, it will be sunny.
Fresh snow
Above approximately 2200 m:
Northern flank of the Alps from the eastern Bernese Alps as far as Liechtenstein, northern Grisons, northern Lower Engadine: 5 cm; up to 10 cm from place to place.
Temperature
At midday at 2000 m, between +3 °C in the western and the southern regions, and -4 °C in the eastern regions.
Wind
Winds will be northerly to northeasterly:
  • A moderate-strength bise wind will be blowing in the Jura region and the western Prealps during the nighttime hours on Friday; in high alpine regions and in the south, a moderate-to-strong velocity wind will prevail;
  • during the daytime, slackening off and blowing mostly at light-to-moderate strength.
Outlook through Monday, 05.04.2021
Sunday
On Saturday night, skies will be cold and clear. During the daytime on Easter Sunday, it will be predominantly sunny.
The danger of dry-snow avalanches is not expected to change significantly. The danger of wet-snow avalanches will increase during the course of the day, particularly on steep sunny slopes.
Monday
On Easter Monday it will be quite sunny to begin with. During the course of the day, cloud cover will move in from the northwest, accompanied by rising showers. The snowfall level will initially lie at 1200 to 1400 m, subsequently it will descend to below 1000 m. During the afternoon, strong-velocity westerly winds are expected to arise.
The danger of dry-snow avlanches could increase slightly in the northern regions during the afternoon. As a result of descending temperatures, the danger of wet-snow avalanches will diminish.