Hasliberg - Rosenlaui

For those venturing off piste a critical avalanche situation will be encountered in some regions.

The new snow and wind slabs are lying on the unfavourable surface of an old snowpack. Additionally in some places avalanches can also penetrate deep layers and reach dangerously large size. Single winter sport participants can release avalanches very easily. Remotely triggered avalanches are possible. Whumpfing sounds can indicate the danger. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger.

Snowpack In the areas of precipitation, massive to strong-velocity, in some places also storm-strength winds from northerly directions have transported the snow intensively. The fresh snow and freshly generated snowdrift accumulations have been deposited in far-reaching wind-protected terrain distant from ridgelines on top of an unfavourable, expansively metamosphosed (faceted) and loosely-packed old snowpack surface. At heightened altitudes the old snowpack surface manifests pronounced influence from northwesterly winds which were blowing over the last few days and was more favourable. More deeply embedded inside the snow cover from the southern Valais over the Gotthard region as far as Grisons there are numerous softened, expansively metamorphosed (faceted) layers evident between consolidated layers of snow and crusts. These faceted layers are especially pronounced in places where the snowpack is shallow and where one breaks through it down to the ground on skis. On the northern flank of the Alps, the lowermost section of the snow cover is frequently quite well consolidated; however, on top of this layer there are numerous faceted layers embedded in the snowpack. In the northern and the furthermost western part of Lower Valais, the snowpack layering is most favourable and there are hardly any pronounced weak layers evident. Observed weather review Saturday, 04.02.2023 During Friday night there was snowfall in the eastern regions of Switzerland which persisted into the morning hours on Saturday. During the daytime north of the Main Alpine Ridge, skies were heavily overcast for the most part. South of the Main Alpine Ridge it was predominantly sunny. Fresh snow The snowfall level lay mostly between 800 and 1200 m. Between Friday evening and Saturday midday the following amounts of fresh snow were registered:

• central and eastern sectors of the northern flank of the Alps, northern Grisons, northern parts of central Grisons, northern part of Lower Engadine: 10 to 20 cm; as much as approximately 30 cm in northern Prättigau more than anywhere else;
• in the remaining regions of Switzerland, less than 10 cm, or else it remained dry.

Temperature At midday at 2000 m, between -1 °C in the western and the southern regions and -3 °C in the eastern regions. Wind Winds were blowing from northerly directions,

• blowing at strong to storm strength during the nocturnal hours on the northern Alpine Ridge and on the Main Alpine Ridge;
• blowing predominantly at moderate to strong velocity in the other regions of Switzerland and at elevated altitudes.

Weather forecast through Sunday, 05.02.2023 In the morning hours it will be predominantly sunny in the mountains. Subsequently, cloud cover will move in from the north and snowfall will set in, extending down to low lying areas. In the Valais and on the southern flank of the Alps it is expected to remain predominantly sunny until late afternoon. Fresh snow The snowfall level will lie at 800 m. Only a small amount of fresh fallen snow is anticipated:

• in central and eastern sectors of the northern flank of the Alps as well as northern Grisons: only a few centimetres;
• in the other regions of Switzerland it is expected to remain dry.

Temperature At 2000 m, between -2 °C in the southern regions, -4 °C in the western regions, and -8 °C in the eastern regions. Wind Winds will be blowing from northerly directions, generally slackening off somewhat during the course of the day,

• blowing predominantly at moderate strength in the western regions at elevated altitudes;
• blowing at moderate to strong velocity in the eastern and the southern regions at heightened altitudes.

Outlook through Tuesday, 07.02.2023 On Monday it is expected to be quite sunny. During the afternoon in the northern regions, a small amount of snowfall is anticipated which will extend down to low lying areas; snowfall will also set in on Monday night in the southern regions. On Tuesday, it is expected to be predominantly sunny in the mountains. Temperatures will remain low, amid light to moderate-strength northeasterly winds. The avalanche danger levels will incrementally decrease. Nevertheless, in the eastern regions the situation will continue to remain treacherous for backcountry snow sports apart from the secured ski runs.