Lower Valais
Val d'Anniviers
Day Risk Profile
Avalanche Problems
Persistent weak layers
3=
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 + Gliding snow
2
Field notes
Wet snow
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.
Gliding snow
Almost impossible to predict precisely, even when the warning signs are visible. A crack visible on the snowpack surface formed by snow-gliding on steep, and particularly grass-covered slopes. Areas below slopes with visible glide cracks should be avoided whenever possible due to threat of gliding sluffs or avalanches.EAWS glossary — gaps that open in the Snow deposited on the ground in a multiplicity of layers.EAWS glossary down to the ground — are often precursors to release, but they don't tell you when. A glide avalanche can release minutes after the cracks appear, or weeks later, or not at all. Some release without any visible warning. Avoid lingering anywhere near glide cracks: above them, alongside them, or below in the runout.
Snowpack & Weather
Snowpack
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, 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 thickly covered and can only be triggered by human activity in some places. However, avalanches may become very large.
South of the line from the Rhône to the Rhine, the 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 still pronounced. Although there is not quite as much snow here, avalanches can still become large or even very large. In Grisons, avalanche-prone locations are still common, even around the treeline. 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 remote triggering are typical. In southern Valais, the significant weak layers in the lower part of the Snow 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 Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary 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.
Weather review for Monday
In the north, there were small amounts of precipitation during the night, falling as snow above approximately 1600 m. It was very cloudy during the day, but mainly dry. It was partly sunny in the inneralpine regions and beautiful in the south.
Fresh snow
During the night into Monday:
- Along the central and eastern Prealps: about 10 cm
- less elsewhere, dry in the south
Temperature
At midday at 2000 m, between +2°C in the north and a mild +5°C in the south
Wind
Moderate to strong from the west to northwest
Weather forecast to Tuesday
It will be sunny in the west and south. There will be precipitation in the east, falling as snow above approximately 1900 m.
Fresh snow
From Monday until the precipitation ends:
- Prättigau, Silvretta and Samnaun: 10 to 20 cm
- Central and eastern part of the northern flank of the Alps, other regions of northern Grisons and the Lower Engadine: up to 10 cm
However, these precipitation amounts are still unconfirmed.
Temperature
At midday at 2000 m, between a mild +5 °C in the southwest and +1 °C in the northeast
Wind
In the north, moderate to strong westerly winds continue during the night, light winds during the day
On the Main Alpine Ridge and south of it, sometimes stormy during the night at high altitudes, otherwise moderate to strong from the northwest
Outlook to Thursday
Clear nights will be followed by sunny days. With a zero-degree level of 3100 m on Wednesday and 2700 m on Thursday, it will be extremely mild. The winds will be light at first, then moderate from westerly directions as the day progresses on Thursday.
The danger of dry avalanches will decrease, but only very slowly in southern Valais, Ticino and Grisons due to the pronounced 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. Gliding avalanches are still to be expected, including large avalanches in the west and north.