Persistent weak layers
- All elevations
A generally favourable avalanche situation will prevail.
Single winter sport participants can release avalanches in some places. These can release the weakly bonded old snow as well and reach medium size. The avalanche prone locations are rather rare but are barely recognisable, even to the trained eye. In addition small wind slabs will form in particular at elevated altitudes. These are in some cases prone to triggering. Backcountry touring calls for careful route selection.
Snowpack Snow depths on flat fields at the measurement stations at high altitudes are recording one-third to two-thirds of otherwise customary snow-depth measurements. With the exception of the northern and the furthermost western parts of the Lower Valais, the snow cover contains expansively metamorphosed (faceted) and loosely-packed layers over widespread areas. On the northern flank of the Alps these layers are frequently located in the uppermost sector of the snow cover; in the southern part of the Valais and in Grisons, the entire snow cover is frequently expansively metamorphosed (faceted) and loosely-packed. The frequency of places where dry-snow slab avalanches can be triggered is diminishing. These places still lie on shady, very steep slopes more than anywhere else. As a consequence of solar radiation and higher daytime temperatures, wet-snow and gliding avalanches are possible on very steep south-facing slopes during the course of the day. In regions where the old snowpack is weak, i.e. where there is a persistent weak layer embedded inside it, wet-snow slab avalanches can also be triggered by persons in isolated cases. Observed weather review Saturday, 18.02.2023 Following a night of predominantly clear skies it was generally sunny and mild on Saturday. Fresh snow - Temperature At midday at 2000 m, predominantly at +6 °C, at +4 °C in the central and eastern sectors of the northern flank of the Alps. Wind Winds were westerly to northwesterly,
Weather forecast through Sunday, 19.02.2023 On Saturday night in the Bernese Oberland, in the Valais and in the Gotthard region, skies are expected to be predominantly clear, in the other regions of Switzerland skies will be intermittently overcast. During the daytime hours of Sunday in the central and eastern sectors of the northern flank of the Alps as well as in the northern parts of Grisons, skies will be variably cloudy to heavily overcast. Particularly in the eastern sector of the northern flank of the Alps above 1500 m, a small amount of snowfall is anticipated. In the remaining regions of Switzerland it is expected to be predominantly sunny. Fresh snow - Temperature At midday at 2000 m, between +3 °C in the western and the southern regions and -2 °C in the eastern regions. Wind Winds will be westerly to northwesterly,
Outlook through Tuesday, 21.02.2023 On Monday in the central and eastern sectors of the northern flank of the Alps, high-foglike residual cloudbanks will persist during the morning hours. In the other regions of Switzerland as well as on Tuesday, it is expected to be sunny. The northwesterly winds will slacken off on Monday. With zero-degree levels at 3000 m, temperatures are inordinately mild for this juncture of the season. The danger of dry-snow avalanches is not expected to change significantly. The danger of wet-snow avalanches on steep sunny slopes is subject to a typical springtime cycle of rising-and-falling danger.
Bulletin data: WSL Institute for Snow and Avalanche Research SLF (CC BY 4.0)