Bollettino valanghe

Gruyère

SLF
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Problemi valanghivi

  • Wind slab

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Snowpack Structure

Snowpack

Before the snowfalls this week, an extensive, cohesive snowpack was present mainly on north-facing slopes above 2800 m and generally in the high Alpine regions. At low and medium altitudes, the fresh snow fell on bare ground. At high altitudes, there was little snow in particular on shady slopes, with terrain roughness mostly not yet levelled out.

With new snow and sometimes storm force winds from the west and south, snowdrifts have formed in the last few days, especially in the west and north also large ones. In the high Alpine regions, this snow lies on an angular, former old snowpack surface, which is still prone to triggering in places.

During the night to Friday, more new snow will fall, which will be transported by strong to storm force northwesterly winds.

Weather Forecast

Weather forecast until Friday, 22.11.2024

In the north it will be overcast and precipitation will fall, heavy during the night, only a little during the day and in showers.

It will clear up on the southern flank of the Alps during the night to Friday. It will be mostly sunny during the day.

Fresh snow

During the first half of the night, the snow line will fall again to low altitudes in the west and it will generally snow down to low-lying areas. The following amounts of new snow are expected:

  • extreme west of Lower Valais, Northern Alpine Ridge, northern Prättigau: 20 to 40 cm, and locally up to 50 cm;
  • rest of northern flank of the Alps, Goms, rest of Gotthard region, rest of northern Grisons: 15 to 30 cm;
  • otherwise mostly 10 to 20 cm

Temperature

At midday at 2000 m, around -12 °C.

Wind

  • Generally strong to stormy from the southwest during the first half of the night in the west and at high altitudes, otherwise weak to moderate
  • Then strong to stormy from the northwest on the Northern Alpine Ridge and the Main Alpine Ridge, moderate to strong northerly winds on the southern flank of the Alps

Weather Review

Weather review for Thursday, 21.11.2024

After clearing up during the night and in the early morning, it rapidly clouded over in the late morning. It was then mostly very cloudy with precipitation.

Fresh snow

The snow line was at low altitude, but climbed towards 1600 m in the afternoon on the northern flank of the Alps and in Lower Valais from the west. It has been snowing since Wednesday afternoon:

  • in Lower Valais and the Vaud Alps: widespread 15 to 30 cm
  • in the rest of Valais, on the remaining northern flank of the Alps and in northern Grisons: 5 to 15 cm;
  • less elsewhere.

From the start of the precipitation on Tuesday morning until Thursday afternoon, precipitation fell above approximately 2200 m:

  • westernmost Lower Valais, northern Valais: 50 to 80 cm, with up to 100 cm on the border with France;
  • rest of the Northern Alpine Ridge to the Glarus Alps, Vaud Alps, southern Bernese Oberland, rest of Valais, Gotthard region: mostly 20 to 40 cm
  • otherwise widespread 5 to 20 cm, less in the Jura and in the very south

Temperature

At midday at 2000 m, between -6 °C in the west and -10 °C in the east.

Wind

  • Moderate to strong westerly winds during the night to Thursday at altitude, then subsiding
  • Turning south in the late morning and strong to stormy

Tendency

Outlook

At the weekend it will be mostly sunny and significantly warmer. In the north, the zero-degree level will increase to around 3000 metres on Sunday, in the south it will be around 1600 metres. The wind will be mostly moderate from southerly directions at high altitudes and there will be a foehn wind in the Alpine valleys of the north.

The danger of dry avalanches will decrease. With the significant consequences of warming and solar radiation, loose snow slides are expected; in areas with lots of fresh snow, even higher ones.

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

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