Waadtländer Voralpen

Considerable avalanche danger will be encountered over a wide area.

As a consequence of a strong westerly wind, wind slabs formed on Thursday over a wide area. As a consequence of new snow and strong wind these will increase in size additionally. Avalanches can be released by a single winter sport participant. Additionally in very isolated cases avalanches can be released in the old snowpack and reach large size. These avalanche prone locations are to be found in particular on north facing slopes above approximately 2400 m and on south facing slopes above approximately 2800 m. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger.

Snowpack As a consequence of strong-velocity winds, snowdrift accumulations which are prone to triggering have been generated in many places. On Friday a small amount of fresh snow will be delivered on the wings of a continuingly strong-velocity westerly wind and with it, particularly on the northern flank of the Alps, further snowdrift accumulations will be generated. The fresh fallen snow and freshly generated snowdrifts in the western and the northern regions from the beginning of the week are settling to an increasing degree and stabilising; nevertheless, from place to place they can still be triggered. Deeply embedded inside the old snowpack there are expansively metamorphosed (faceted) and loosely-pacekd layers of snow evident. These layers, ranging particularly from southern Valais over the Gotthard region as far as Grisons, are prone to triggering. In the remaining regions of Switzerland these weak layers occur more seldom or are no longer likely to trigger. The weak layers are located on north-facing slopes above 2200 to 2400 m, and on south-facing slopes above approximately 2800 m. Observed weather review Thursday, 12.01.2023 In the early part of the night on the northern flank of the Alps, in the Valais as well as in northern Grisons, there was a small amount of precipitation. The snowfall level descended from 1700 m down to 1000 m. In the other regions of Switzerland it remained dry, with clear skies. During the morning hours, new cloud cover rapidly moved in from the northwest. But conditions remained dry. Fresh snow Between Wednesday midday and Thursday morning the following amounts of fresh snow were registered above 2000 m:

• northern flank of the Alps, Lower Valais: 5 to 15 cm;
• in the remaining regions of Switzerland, only a few centimetres; on the southern flank of the Alps it remained dry.

Temperature At midday at 2000 m, -1 °C. Wind

• Winds in the northern regions and in general at higher elevations were blowing at strong velocity from westerly directions;
• in the southern regions, northerly winds were blowing temporarily at strong velocity during the nighttime hours,
• in the other regions of Switzerland, winds were blowing predominantly at moderate strength.

Weather forecast through Friday, 13.01.2023 Nocturnal skies in the northern regions will be overcast, in the southern regions skies will be partly clear. As early morning approaches in the Jura region and on the northern flank of the Alps, precipitation is expected to set in. During the daytime hours in the northern regions, skies will be overcast accompanied by precipitation. The snowfall level will descend from 1400 m down to nearly 1000 m. In the southern regions it will be quite sunny. Fresh snow By Friday afternoon, the following amounts of fresh snow are anticipated above 1600 m:

• northern flank of the Alps, Lower Valais, northern Prättigau, Jura region: 5 to 15 cm; in the western Jura region 20 cm from place to place;
• in the remaining regions of Switzerland, only a few centimetres; on the southern flank of the Alps it will remain dry.

Temperature At midday at 2000 m, between -3 °C in the northern regions and -1 °C in the southern regions. Wind The westerly winds will be blowing at strong velocity, intermittently at storm strength, on the northern flank of the Alps as well as in general at high altitudes; in the other regions of Switzerland, winds will be blowing predominantly at moderate strength. Outlook through Sunday, 15.01.2023 Saturday In the inneralpine regions and on the southern flank of the Alps it will be partly sunny. In the western and the northern regions skies will be predominantly overcast. It is expected to remain dry. Avalanche danger levels will incrementally decrease. Sunday On Saturday night in the northern and the western regions, precipitation will set in, subsequently precipitation will intensify on Sunday. The snowfall level will ascend during Saturday night to nearly 2000 m, subsequently desend down to low lying areas during the course of the day on Sunday. Winds will blowing at strong to storm strength from westerly directions at elevated altitudes. Avalanche danger levels are expected to increase somewhat in the northern and the western regions as a result of fresh fallen snow and winds.