Bulletin d’avalanche

Waadtländer Voralpen

SLF
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Danger d’avalanche

All elevations
2+ · Modéré
Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Problèmes avalancheux

  • Wind slab

    • Above 1,800 m
  • Wet snow

    • Below 2,600 m
  • Gliding snow

    • Below 2,600 m

Snowpack Structure

Snowpack

A snowfall period lasting several days has begun in the south. In the north, drift snow has started to form with the foehn wind and this will continue over the weekend. The old snowpack is mostly well consolidated under the new and drift snow. At the transition to the old snowpack, however, there is a weak layer with a crystal structure in some places, especially in the inneralpine regions.

As temperatures rise, the layers of fresh snow are becoming increasingly soaked. Before the onset of the wintry weather, the old snowpack on east-, south- and west-facing slopes was already soaked up to above 3000 m and on north-facing slopes up to approximately 2500 m. Gliding avalanches are still possible, especially in the areas of the north that have received a lot of new snow. This is particularly the case on slopes that were bare prior to these snowfalls.

Weather Forecast

Weather forecast until Saturday, 27.04.2024

In the south, it will be very cloudy and snow will fall. The snowfall level will rise from 1600 to 1900 m. It will be partly sunny in the northwest and mostly sunny in the northeast.

New snow

From Friday afternoon to Saturday afternoon, the following amounts of fresh snow are expected above approximately 2000 m:

  • Main Alpine Ridge from the Great St Bernard Pass to Rheinwald and south of this: 15 to 30 cm;
  • neighbouring regions to the north and along the Northern Alpine Ridge from the Diablerets to the Gotthard region: 5 to 10 cm.

Temperature

At midday at 2000 m, between +4 °C in the north and 0 °C in the south.

Wind

  • There will be a moderate to strong southerly wind at high altitudes.
  • In the north, a moderate to strong foehn wind will blow down into the valleys.

Weather Review

Weather review for Friday, 26.04.2024

It was overcast in the south and snow began to fall above around 1400 m. In the north, it was partly sunny with an increasing foehn wind.

New snow

From Thursday afternoon to Friday afternoon, 5 to 15 cm of fresh snow was recorded in the Simplon region and on the central part of the southern flank of the Alps above approximately 1600 m.

Temperature

At midday at 2000 m, between 0 °C in the north and -3 °C in the south.

Wind

There was a light to moderate southwesterly wind, with an increasing foehn wind in the north as the day progressed.

Tendency

Trend until Monday, 29.04.2024

The snowfall will intensify in the south during Saturday night into Sunday. The snowfall level will rise to around 2200 m and drop again slightly during the day on Sunday. On the Main Alpine Ridge from the Great St Bernard Pass to the Lukmanier Pass and neighbouring areas to the south, 30 to 50 cm of new snow is expected at high altitudes. Strong southerly winds will blow at high altitudes, and strong to storm-force foehn winds into the valleys in the north. The danger of dry avalanches will increase significantly in the south with the new snow and wind. At high altitudes, level 4 (high) may be reached, and wet avalanches are to be expected with rain at intermediate altitudes, especially on north-facing slopes. In the north, the avalanche situation will not change significantly, with drifting snow representing the main danger.

Monday will be changeable and cloudy widely, with only a little snow in the south. The foehn wind in the north will continue, but become lighter. The danger of dry avalanches will slowly decrease.

Gliding avalanches will still be possible, and increasingly also again at high altitudes in the north as a consequence of warming temperatures.

Bulletin data: WSL Institute for Snow and Avalanche Research SLF (CC BY 4.0)

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