Lower Valais
Val d'Anniviers
Day Risk Profile
Problem type changes as the day progresses
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 + 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
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 and are now hardly triggerable by human activity.
In the regions south of a 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 that have been a feature since the beginning of January are still present. However, the number of avalanche-prone locations is continuing to decrease. Isolated danger signs have still been observed in the last few days, particularly in Grisons and eastern Ticino, and dry avalanches have been triggered in deeper layers of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary, including large ones.
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 lower part of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary are being weakened as they become moistened for the first time. Wet The abrupt release of a slab of snow on a mountain slope. After crack initiation and crack propagation in a weak layer the released slab comprises 3 elements: The weak layer, the gliding horizon and the slab. If the slope angle is steep enough, the slab will glide down. If the slope is not steep enough, the slab will settle down on the failed weak layer. Possibly a whumpf sound will follow due to air pressed out of the weak layer. The fracture line will be sharp edged.EAWS glossary are possible as the day progresses. These can occur naturally but can also be occasionally triggered by winter sports participants, at present mainly on sunny slopes below approximately 2600 m. Isolated gliding avalanches are also possible here. Gliding avalanches can become large, especially in the snowier west.
Weather review for Sunday
After a clear night, it was mostly sunny. Visibility was still somewhat obscured by Sahara dust. Cumulus clouds formed in the Jura, the Prealps and in the south.
Fresh snow
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Temperature
At midday at 2000 m, between +3 °C in the north and +1 °C in the south
Wind
Mainly light from the south to southeast
Weather forecast to Monday
The night will only be partly clear in the south and south-east but mostly clear elsewhere. During the day it will be quite sunny in the mountains, with patches of cloud, especially in the east. In the Jura and the Prealps, there will be an increase in cumulus clouds and isolated rain showers will be possible. The obscuring of visibility due to Sahara dust will decrease. In the south, cloud cover will increase as the day progresses and light showers will be possible in some localities. The snowfall level will be between 1400 m and 1600 m.
Fresh snow
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Temperature
At midday at 2000 m, around +2 °C in the north and -1 °C in the south
Wind
Mostly weak from south to southwest, picking up somewhat as the day progresses
Outlook to Wednesday
The nights will be mostly clear in the east, but only partially clear in the west and south. During the day on both days, it will be partly sunny with variable cloud cover in the north and often cloudy in the south. Weak showers are possible, especially in the Jura and in the south, then on Wednesday also on the western part of the northern flank of the Alps and in the Prealps. The snowfall level will be between 1400 and 1700 m. The southwesterly wind will be mostly weak at first, but will pick up as the day progresses on Wednesday.
The danger of dry avalanches will not change significantly. The danger of wet and gliding avalanches will increase somewhat as each day progresses. Touring and off-piste descents should be completed in good time.