Vaud Alps
Bex-Villars
Avalanche Problems
Wind slab + Persistent weak layers
2=
Field notes
Wind slab
Look for fresh snow deposits on Slope facing downwind/ wind sheltered aspect. Snow deposits can attain several times average snow depth.EAWS glossary, in Usually a steep, elongated, eroded trench; typically prone to snowdrift accumulation.EAWS glossary and Rounded or elongated concavity; typically tending to accumulate snowdrift.EAWS glossary, and behind ridgelines and abrupt changes in terrain — these are where the wind has loaded the snow into slabs that are easy to trigger. Recent avalanches, shooting cracks under your weight, and 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 are clear confirmations of the problem. The safest move is to avoid wind-loaded terrain entirely. NB wind signs alone don't always mean an avalanche problem exists, and the age of drifted snow is hard to judge.
Persistent weak layers
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
On northern slopes, the snowline is around 2000 m and on southern slopes between 2400 m and 2800 m. At high altitudes, there are patches of continuous Snow deposited on the ground in a multiplicity of layers.EAWS glossary in Usually a steep, elongated, eroded trench; typically prone to snowdrift accumulation.EAWS glossary and Rounded or elongated concavity; typically tending to accumulate snowdrift.EAWS glossary on shady slopes. The snow is significantly deeper above 2800 m.
On Saturday, precipitation set in in the south. Conditions had previously been generally dry and sunny in the mountains over the last two weeks. While the snow had largely melted on steep south-facing slopes at high altitudes over this period, on shady slopes and generally in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary, the Snow deposited on the ground in a multiplicity of layers.EAWS glossary had begun to become faceted. Distinct 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 had formed. Avalanches can easily be triggered where fresh and drifted snow falls on this snowpack.
Outlook
A further 5 to 20 cm of snow will fall above 1000 m in the north by the night to Tuesday with sometimes strong north to northeasterly winds. On Tuesday and Wednesday, conditions will be mostly sunny with zero-degree levels between 1000 m and 1400 m. The wind will be light to moderate and shift from northeast to southwest on Wednesday.
Avalanche risk will hardly change on Tuesday and will decrease slowly on Wednesday.