Bergell, Poschiavo, Münstertal
Bergell
Avalanche Problems
Persistent weak layers
2-
Field notes
Persistent Snowpack 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 very challenging to recognise. Distinctive 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 shooting cracks are typical when present, but you can have a serious weak layer with no warning signs at the surface. Knowledge of how the Snow deposited on the ground in a multiplicity of layers.EAWS glossary has evolved is essential. SLF's travel advice is direct: travel conservatively, avoid terrain where the consequences of being caught are large, and treat the history of weather and snow as more important than what you can see today. Read the full bulletin.
Wet snow
2
Field notes
Rolling snowballs, deep penetration when you step or ski, and small natural slides are clear signals that the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is losing strength. After a clear, cold night the surface often freezes into a strong supporting Layer of hard-compacted snow resulting from a melt-freeze process or wind.EAWS glossary, and conditions are favourable in the early morning. After a warm, overcast night, the problem may be present from the start of the day. Plan early returns and watch the runout zones below you.
Snowpack & Weather
Snowpack
Saturation of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is well advanced. The most precarious areas are slopes where Snowpack 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 Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary are becoming wet for the first time. At present, this is mainly affecting north-facing slopes between approximately 2200 and 2600 m, and east- and west-facing slopes between approximately 2500 and 3000 m. In many places, steep south-facing slopes are snow-free up to around 3000 m; where there is still snow, it is wet as far as the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary.
In the mostly clear overnight conditions, the surface of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary freezes and becomes load-bearing before softening over the course of the day.
Weather review for Friday
In the north, it was sunny after a clear night. In the south, it was cloudy with bright spells during the day.
Fresh snow
-
Temperature
At midday at 2000 m, between +9 °C in the north and +4 °C in the south
Wind
Mainly light
Weather forecast to Saturday
Overnight to Saturday, there will be patchy cloud in the west with skies mostly being clear elsewhere. During the day, it will be mostly sunny, but cumulus clouds will develop in the west and south and there is a possibility of isolated showers.
Fresh snow
-
Temperature
At midday at 2000 m, between +9 °C in the north and +6 °C in the south
Wind
Mainly light
Outlook
Sunday
There will be patchy cloud overnight to Sunday. During the day, it will be mostly sunny in the east. In the west and south, it will be cloudy with some bright spells and there is a possibility of isolated showers in the afternoon. There will be moderate winds at times from southerly directions.
Due to reduced outgoing longwave radiation overnight and with sunshine in the east, the danger of wet avalanches will increase more quickly than on the last few days.
Monday
Sunday night into Monday will be cloudy. During the day, there will still be some bright spells in the east, and some showers along the main Alpine ridge. The snowfall level will be around 2300 m. The wind will be moderate to strong from southerly directions.
The danger of dry avalanches may increase slightly in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. The danger of wet avalanches will increase from the morning onwards where there is reduced outgoing longwave radiation overnight and rainfall.