Bulletin d’avalanche

Gadmertal

SLF
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Danger d’avalanche

All elevations
2 · Modéré
Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Weather Synopsis

Nocturnal skies on Tuesday night were clear in the western and southern regions. In the northern and the eastern regions skies were partly overcast, accompanied by light showers. The snowfall level lay at 1400 m. During the daytime on Wednesday it was predominantly sunny. Fresh snow: On Tuesday night in the northern and eastern regions there was a small amount of fresh snow registered. Between Sunday evening and Wednesday morning, the following amounts of fresh snow were registered overall above approximately 2200 m:

  • Temperature: At midday at 2000 m, +4 °C in the western and the southern regions and 0 °C in the eastern regions. Wind: Winds were blowing at light to moderate strength from northeasterly to northwesterly directions. Following a night of predominantly clear skies it will be sunny on Thursday accompanied by isolated convective clouds during the course of the day. The zero-degree level will ascend to approximately 3000 m. Fresh snow: - Temperature: Temperatures are expected to continue climbing. At midday at 2000 m: between +7 °C in the western regions and +4 °C in the eastern regions. Wind: Winds will be blowing at light to moderate strength from the northeast.

Avalanche Activity

The wind slabs of the last few days are in some cases prone to triggering. The number and size of avalanche prone locations will increase with altitude. In high Alpine regions the danger of dry avalanches is a little higher. Avalanches can in some places be released by people and reach large size in isolated cases. Backcountry touring calls for meticulous route selection. Medium-sized and, in isolated cases, large wet avalanches are possible. This applies in particular on north facing slopes below approximately 2400 m, as well as on east, south and west facing slopes below approximately 3000 m. Backcountry tours and ascents to alpine cabins should be concluded timely.

Snowpack Structure

The fresh fallen snow in the northern regions from the beginning of this week, together with the freshly generated snowdrift accumulations, are still prone to triggering in some places on north-facing and east-facing slopes at high altitudes more than anywhere else. This has been confirmed by isolated avalanche triggerings from Wednesday. During Wednesday night, a melt-freeze crust will form on the snowpack surface which in the northern and the eastern regions will be breakable in some places. Beneath the fresh fallen snow the snowpack is thoroughly wet on south-facing slopes far up into high alpine regions, on west-facing and east-facing slopes below approximately 3000 m, and on north-facing slopes below approximately 2400 m.

Tendency

Friday: Following a night of clear skies with adequate outgoing longwave radiation conditions it will be quite sunny on Friday accompanied by convective cloud build-up during the course of the day. In the afternoon, high-altitude cloudbanks will move in from the west. The zero-degree level will lie at 3000 m. Winds will be blowing at light to moderate strength and shift from northeasterly to westerly. The danger of dry-snow avalanches will continue to diminish, however avalanches triggered by persons are still possible in places, particularly on north-facing slopes in high alpine regions. The danger of wet-snow avalanches is low after the clear nighttime skies, nevertheless will increase swiftly with the solar radiation and daytime warming during the course of the morning hours. Saturday: Nocturnal skies Friday night will to an increasing degree be heavily overcast from the west and precipitation is expected to set in. During the daytime hours on Saturday, skies will be variably cloudy. Intermittently, a small amount of precipitation can be expected, but also some bright intervals are possible. The snowfall level will descend to approximately 2000 m. On the northern flank of the Alps and in the Lower Valais, 10 to 20 cm of fresh snow is possible at high altitudes, less in the other regions of Switzerland. Winds will be blowing for the most part at moderate strength from westerly directions. The danger of dry-snow avalanches could increase slightly from region to region. The danger of wet-snow avalanches is expected to decrease somewhat.

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

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