Appenzeller Alpen

The new snow and wind-drifted snow layers from Sunday are prone to triggering. These are most pronounced in western Ticino and on the western and central parts of the Northern Alpine Ridge.

In some places, there is surface hoarTransparent, frequently flat crystals forming on the snowpack when moist air settles on the surface. It forms most often during cold, clear, humid nights. Once it is blanketed by fresh fallen snow, surface hoar is one of the most critical weak layer. See also: www.snowcrystals.itEAWS glossary buried slightly deeper in the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary. In this weak layerSnowpack layer in which the crystals are poorly bonded and the layer has the potential to fail. Typical crystals in dry weak layers causing avalanches are : precipitation particles; surface hoar; faceted crystals; hollow crystals; graupel. Generally >1mm in size, loose grains with few bonds Wet weak layers can be formed by all snow crystal/grain types.EAWS glossary, avalanches have continued to be triggered in recent days, especially in southern Valais and in Grisons.

In the weak layersSnowpack layer in which the crystals are poorly bonded and the layer has the potential to fail. Typical crystals in dry weak layers causing avalanches are : precipitation particles; surface hoar; faceted crystals; hollow crystals; graupel. Generally >1mm in size, loose grains with few bonds Wet weak layers can be formed by all snow crystal/grain types.EAWS glossary near the ground, few avalanches have continued to be triggered recently, especially in the inneralpine regions and southern parts of Grisons. In the other regions, there are still weak layers in the near-ground old snowpackSnow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary in some places on shady slopes, but they are mostly so thickly covered that they are hardly prone to triggering.

During the night into Sunday, snow fell above approximately 1200 m, mostly in the south. During the day it was fairly sunny in the north. In the far west and in the south, the snowfall ended in the morning. However, it remained largely cloudy.

Fresh snow

From Saturday afternoon to Sunday afternoon, the following amounts of snow will fall above approximately 1500 m:

• Western Ticino: 20 to 40 cm
• Valais, remaining central part of the Main Alpine Ridge and to the south of it, Avers, Val Bregaglia: 10 to 20 cm
• Elsewhere, a few centimetres over a wide area; dry in the north-east

Temperature

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

Wind

From southerly directions

• Mostly moderate and sometimes strong on the Main Alpine Ridge and the Northern Alpine Ridge
• Elsewhere light to moderate

In the north there will be broken cloud cover with local showers. The snowfall level will be 1300 m. It will be sunny in the south.

Fresh snow

A few centimetres locally in the north

Temperature

At midday at 2000 m, around -2 °C

Wind

Mostly light, at times moderate from the north on the Main Alpine Ridge

Tuesday

After a clear night it will be sunny. Winds will be light. The zero-degree level will be at 2000 m. The danger of dry avalanches will decrease. Wet avalanches are unlikely to occur during the course of the day.

Wednesday

After a partly clear night, snowfall will set in from the north-west as the day progresses. In the east there will be prolonged bright spells and in the south it will be fairly sunny. By the evening, 10 to 20 cm of snow will fall on the northern flank of the Alps. The snowfall level will drop from 1200 m to low altitudes by the evening. There will be a strong to storm force wind in the north, and a moderate to strong westerly wind at high altitudes in the south.

The avalanche danger in the north will increase significantly over the course of the day. There will be no significant change in the south.