Appenzeller Alpen

The large volumes of fresh and drifted snow from the last few days and weeks remain prone to triggering in many places.

North of a line from the Rhône to the Rhine and in the extreme west of Lower Valais, 2 to 3.5 m of snow have fallen over the last two weeks. As a result, 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 in the old snowpackSnow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary are thickly covered and are now barely triggerable by human activity. However, avalanches can occasionally propagate into deep layers, becoming very large as a result.

South of the line from the Rhône to the Rhine, the persistent 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 are still pronounced. The weakly bonded old snowpackSnow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary is most prone to triggering in Grisons, where avalanche-prone locations are still common, even around the treeline. WhumpfingDistinctive noise (resembling a “whumpf” sound) occurring when a weak layer beneath a slab collapses. The air of the weak layer is forced outside the snowpack, with the resulting whumpf sound being heard. The sound usually indicates an unstable situation and can be accompanied by surface cracking. A whumpf is a clear avalanche alert.EAWS glossary sounds and remote triggering are typical. In southern Valais, the significant weak layers in the lower part of the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary are mostly rather more thickly covered. Avalanche-prone locations where avalanches can be triggered in the weak old snowpack are therefore somewhat less frequent and mainly located in areas with little snow.

With the mild temperatures, medium to large gliding avalanches are to be expected on steep grassy slopes below approximately 2000 m.

The precipitation ended during the night into Sunday, most recently in the east. When the precipitation ended, the snowfall level was around 1500 m. It was quite sunny during the day.

Fresh snow

From Saturday afternoon to Sunday morning above 2000 m:

• Eastern part of the northern flank of the Alps, northern Grisons, Lower Engadine: 15 to 25 cm
• Central part of the northern flank of the Alps, northern Upper Valais, rest of Grisons: 5 to 15 cm

Since this period of precipitation began on Friday evening, the following amounts of snow have fallen above 2000 m:

• Eastern part of the northern flank of the Alps, Prättigau, Silvretta, Samnaun: 40 to 60 cm
• Remaining northern flank of the Alps, northern Upper Valais, Goms, rest of northern Grisons, rest of Lower Engadine: 20 to 40 cm
• Elsewhere: a widespread 10 to 20 cm, dry in the south

Temperature

At midday at 2000 m, between +2 °C in the north and +5 °C in the south

Wind

• Moderate to strong during the night, sometimes stormy on the Main Alpine Ridge, from west to northwest
• During the day, moderate southwesterly winds in the north, light winds in the south

There will be widespread precipitation during the night and in the late morning. As the day progresses, there will be bright spells. In the south it will be dry and mostly sunny during the day. The snowfall level will be between 1600 m and 1800 m in the north, while in southern Valais it may rise to around 2000 m.

Fresh snow

From Sunday evening to Monday afternoon above 2200 m:

• Northern Alpine Ridge: 5 to 10 cm
• Remaining northern flank of the Alps, rest of Valais, rest of northern Grisons, northern Lower Engadine: a few centimetres

Temperature

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

Wind

Westerly to northwesterly winds, moderate in many places and strong at high altitudes

On Tuesday, snow will fall on the eastern part of the northern flank of the Alps and in northern Grisons above 1800 m. 10 to 20 cm of new snow is to be expected at high altitudes. However, the quantities are still uncertain. It will be sunny and very mild in the west and south. The northwesterly wind will be strong at times during the night into Tuesday, then it will ease. On Wednesday it will be sunny with light winds and very mild, with a zero-degree level of around 3000 m.

The danger of dry avalanches will not change significantly on Tuesday in the areas with new fallen snow, otherwise it will decrease; however, it will only decrease very slowly in southern Valais, Ticino and Grisons due to the pronounced 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. Gliding avalanches are to be expected, including large avalanches in the west and north.