Waadtländer Voralpen

In the west and in the north a considerable avalanche danger will be encountered over a wide area, especially at elevated altitudes

In the west and in the north a considerable avalanche danger will be encountered over a wide area, especially at elevated altitudes

Dry avalanches are no longer to be expected. As the day progresses gliding avalanches and moist snow slides are possible. Caution is to be exercised in areas with glide cracks.

In the period from Thursday to Sunday, 40 to 60 cm of snow fell in the north over a wide area and as much as 120 cm fell in the west. In some places this snow has not yet bonded well with the old snowpack underneath. The bonding is expected to improve quickly. More conspicuous is the weak layer above the crust containing the Saharan dust. At the weekend, numerous avalanche releases – many of them triggered by people – were reported in this layer, in particular in Valais and on the northern Alpine ridge. Both the prevalence and the further development of these weak layers is uncertain. There were no reports of fractures occurring in even deeper layers of the snowpack. The fresh snow quickly became moist all the way through on steep sunny slopes in particular. In view of the predicted Saharan dust, a further injection of heat into the snowpack is to be expected. Moist and wet snow slides are to be expected, initially originating from the fresh snow in particular. The gliding avalanche activity will increase again, in particular on the northern Alpine ridge.

With quite clear skies on Sunday night, the outgoing longwave radiation was good. During the day the weather was sunny, but for some high-altitude cloudbanks and scattered convective cloud. Fresh snow: - Temperature: At midday at 2000 m: between +5 °C in the north and +1 °C in the south Wind: Light to moderate from westerly directions Monday night will be quite clear, but for some high-altitude cloudbanks. During the day the cloud will become more dense and the Saharan dust will impair visibility. Fresh snow: - Temperature: Increasing significantly, at midday at 2000 m reaching between +10 °C in the north and +4 °C in the south Wind: - Light to moderate from the southwest - In the northern Alpine valleys, a slight foehn tendency

The haze caused by Saharan dust will persist. Wednesday will be dry, and on Thursday there will be showers in the north as the day progresses. It will remain mild, and during the night the outgoing longwave radiation will be reduced. In consequence, the snowpack will again become increasingly moist. Aspects and altitude zones in which the snowpack was not already moist before last week’s major snowfall, however, are unlikely to become moist all the way through. Wet snow avalanches, in particular originating in the near-surface layers, are to be expected. The danger of dry avalanches will continue to decrease slowly.