Waadtländer Voralpen

Considerable avalanche danger will be encountered in some regions.

As a consequence of a gathering strong northeasterly wind, wind slabs will form in the course of the day. In addition the older wind slabs of the last few days are prone to triggering in some cases still. Single winter sport participants can release avalanches, including medium-sized ones. Backcountry touring and other off-piste activities call for careful route selection.

Snowpack As a consequence of moderate to strong-velocity northeasterly winds and increasingly strong bise wind, freshly generated snowdrift accumulations will be formed in the Prealps and in general at high altitudes during the course of the day. The immense amounts of fresh fallen snow and the deep snowdrift accumulations in western regions from this week are settling and stabilising to an increasing degree in spite of the low temperatures. In more deeply embedded layers inside the snowpack there are expansively metamorphosed (faceted) crystals evident which constitute weak layers, particularly on north-facing slopes above 2200 m and on south-facing slopes above approximately 2800 m. These weak layers are prone to triggering in the southern Valais and in Grisons more than anywhere else, as stability tests and avalanche releases this week have confirmed. Observed weather review Friday, 20.01.2023 In the western and the southern regions skies were quite sunny to start with, subsequently cloud cover moved in over widespread areas during the course of the afternoon. In the eastern regions skies were variably cloudy to heavily overcast and there was a small amount of snowfall. Fresh snow - Temperature At midday at 2000 m, between -13 °C in the northern regions and -10 °C in the southern regions. Wind

• Winds in the northern regions were blowing at light to moderate strength from northerly directions;
• winds in the southern regions were blowing at moderate strength, at strong velocity during the afternoon, from northerly directions;
• blowing at strong velocity from northerly directions also in other parts of the Main Alpine Ridge during the afternoon hours.

Weather forecast through Saturday, 21.01.2023 In the northern regions skies will be variably cloudy, in the eastern regions a small amount of snowfall is anticipated. In the southern regions and in the Valais, it will be quite sunny. It is expected to remain cold. Fresh snow Between Friday afternoon and Saturday afternoon the following amounts of fresh snow were registered above 600 m:

• eastern sector of the northern flank of the Alps and northern Grisons: 5 to 10 cm;
• in the remaining regions of Switzerland, only a few centimetres; in the Valais and in the southern regions it remained dry.

Temperature At midday at 2000 m, -12 °C in the northern regions and -9 °C in the southern regions. Wind Winds are expected to be blowing predominantly at moderate strength to begin with; in the Jura region, in the Prealps as well as in general at elevated altitudes, winds will be blowing at increasingly strong velocity from northeasterly directions. Outlook through Monday, 23.01.2023 In the northern regions skies will be heavily overcast on both days for the most part. Intermittently in the eastern regions, a bit of snowfall is anticipated. In the Valais and in the southern regions it will be rather sunny. On the northern flank of the Alps as well as in general at elevated altitudes, a moderate to strong-velocity northeasterly wind will be blowing on Sunday; on Monday, the wind will shift to easterly. The low temperatures are expected to persist. As a result of winds, snowdrift accumulations are expected to be generated from region to region. Avalanche danger levels are not expected to change significantly.