Upper Engadine and Silvretta
Val Chamuera
Day Risk Profile
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.
Snowpack & Weather
Snowpack
In the regions south of a line from the Rhône to the Rhine, the 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 that have persisted since the beginning of January are still present. The number of places where human activity can trigger avalanches in the weak layers of the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary has now decreased significantly. However, any avalanches may still become large.
In the regions north of a line from the Rhône to the Rhine and in the extreme west of Lower Valais, 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 deposited on the ground in a multiplicity of layers.EAWS glossary are mostly thickly covered. Triggering by human activity is unlikely.
With temperatures falling, further moistening of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary and deeper 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 has slowed down. Gliding avalanche activity has also decreased significantly over the last few days.
Weather review for Wednesday
Overnight to Wednesday, conditions were cloudy with clear intervals. There was a little precipitation on the northern and southern flanks of the Alps, falling as snow above approximately 1700 m. During the day, conditions were mostly sunny in the inneralpine regions of Valais and Grisons, while elsewhere, there were only sunny intervals and it was very cloudy on the southern flank of the Alps.
Fresh snow
Along the Prealps and on the southern flank of the Alps: a widespread few centimetres, locally up to 15 cm
Temperature
At midday at 2000 m, between +1 °C in the north and -1 °C in the south
Wind
Light to moderate southwesterly
Weather forecast to Thursday
Overnight to Thursday, conditions will be mostly cloudy, with some snowfall above approximately 1200 m. During the day, the west and south will gradually become sunny, while the central and eastern parts of the northern flank of the Alps and northern Grisons will see only sunny intervals.
Fresh snow
From Wednesday evening to Thursday morning, above 1500 m:
- extreme west of Lower Valais, northern flank of the Alps, Jura: 10 to 25 cm
- rest of Valais and northern Grisons: 5 to 10 cm
- elsewhere a widespread few centimetres
Temperature
At midday at 2000 m, between -2 °C in the north and +1 °C in the south
Wind
- During the night in the north initially moderate to strong from westerly directions, then easing and veering to the north
- Mostly light during the day
Outlook
Friday
Overnight to Friday, conditions will mostly be clear. During the day, it will be mostly sunny in the north, with sunny intervals in the south. With a freshening southwesterly wind, the north will become appreciably milder.
The danger of dry avalanches will not change significantly. The danger of wet and gliding avalanches will increase a little during the day, especially in the north. Touring and off-piste descents should be completed in good time.
Saturday
Overnight to Saturday, conditions will be mostly cloudy, with precipitation in the south. During the day, there will be widespread precipitation, with only the far east remaining dry. The snowfall level will drop from 1500 m to around 1100 m in the south and 700 m in the north. Around 20 to 40 cm of snow will fall on the central part of the main Alpine ridge and south of there by the evening; however, the amounts are still uncertain. There will be a light to moderate southerly wind.
The danger of dry avalanches will increase with the fresh snowfall, significantly on the central part of the main Alpine ridge and south of there, where naturally triggered avalanches will increasingly be possible.