Gruyère

As a consequence of new snow and stormy weather a considerable avalanche danger will be encountered over a wide area.

Snowpack

The freshly fallen snow and the snowdrift deposited during the night is still prone to triggering during the day on Sunday. In the north, the snow cover surface will become wet with rain on Saturday evening up to 2000 to 2400 m. Below about 2400 m, gliding avalanches are still expected on slippery ground in all aspects. At high altitudes, there is about twice as much snow as there normally is at the beginning of December. The snowpack has a favourable structure, apart from thin weak layers of angular crystals deep in the snowpack in the area of older rain crusts. With all the new snow and intense rain, these weak layers could be reactivated in the next few days. In the south, the snow depths are below average and the weak layers are therefore closer to the surface. Especially there, the older weak layers can also be partially released by people.

Weather forecast through Sunday, 10.12.2023

Rainfall will be widespread until Sunday morning, with intense rain in the west and north. The snowfall level will increase briefly to 2000 to 2400 m in the north and far west on Saturday evening, otherwise it will be around 1200 m. On Sunday, it will be mostly dry during the day and quite sunny in the west and south.

Fresh snow

From Saturday afternoon to Sunday morning above approximately 2400 m:

• Northern Alpine Ridge, extreme west of Lower Valais: 30 to 50 cm;
• other regions of Valais, the Gotthard region and northern Grisons, as well as northern Lower Engadine: 20 to 30 cm;
• otherwise widespread 10 to 20 cm, less in the far south.

The Jura will see 20 to 30 mm of rain.

Temperature

At midday at 2000 m, between -3 °C in the west and south, and -5 °C in the northeast.

Wind

• There will be moderate winds, with the northern flank of the Alps seeing a strong to storm-strength westerly wind on Saturday evening.
• In the high Alpine regions, there will be constant strong to stormy winds from west to northwest.

Observed weather review Saturday, 09.12.2023

A little snow fell in the north on Friday evening, then it was dry. On Saturday, it was initially brighter in the east, then cloudy, and precipitation set in from the west.

Fresh snow

From Friday to Saturday afternoon above approximately 1500 m, the following levels were recorded:

• Lower Valais and the northern flank of the Alps: 5 to 10 cm;
• elsewhere: to a lesser extent.

Temperature

At midday at 2000 m, around -2 °C.

Wind

There were weak to moderate winds, with an increasingly strong westerly wind in the afternoon.

Outlook through Tuesday, 12.12.2023

It will be very cloudy with heavy precipitation. The snowfall level will be between 2000 and 2400 m in the west and between 1600 and 2000 m in the east. Above 2500 m, 60 to 100 cm of snow will fall on the northern Alpine Ridge, in Valais and from northern Prättigau to Silvretta, and locally even more is expected in the westernmost and northern Lower Valais and from the western Bernese Oberand to the Central Alps of Switzerland. The westerly wind is often strong. Danger level 4 (high) is expected to be reached in the extreme west of Lower Valais and on parts of the northern Alpine Ridge on Monday, then on Tuesday in large parts of Valais and the northern Alpine Ridge, and possibly also from northern Prättigau to Silvretta. Below 2000 to 2400 m, some large, wet avalanches are expected. Dry avalanches are expected from starting zones at higher altitudes, which will sweep along the increasingly saturated old snowpack in their path and advance into the valleys in the usual avalanche tracks. These avalanches can become very large and exposed parts of transportation routes are at risk. The conditions will be dangerous for winter sports outside marked and open pistes. In the other regions of Grisons, the avalanche danger will also increase, though not as much, with less new snow. In the far south, the avalanche danger will not change significantly in mostly sunny weather.