Lower Valais
Génépi
Hard-to-read day. Considerable, with new snow, persistent weak layers and wet snow in play — you can read the surface problem; the buried one sets the consequence.
Day Risk Profile
Avalanche Problems
New snow + Persistent weak layers
3-
Field notes
New snow
Easy to spot - the snow is fresh. Look at recent avalanche activity in similar terrain, and pay attention to how much new snow has fallen in the last three days. Critical loading depends on temperature, wind, and what was on the surface before the storm. SLF advises waiting until the Snow deposited on the ground in a multiplicity of layers.EAWS glossary has had time to bond before committing to steep terrain in fresh snow.
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.
Wet snow
1
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
The fresh snow and sometimes stormy westerly winds are resulting in snowdrift accumulations. On the northern Alpine ridge and in Valais these are in some cases becoming large, while elsewhere they are mostly medium-sized. Beneath the fresh and drifted snow, the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary contains coarse-grained 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 on steep north-facing slopes at highger altitudes.
Saturation of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is currently scarcely progressing. Avalanche of wet snow masses. Flowing more slowly than dry avalanches; usually for shorter runout distances, however with greater impact on obstacles due to higher snow density.EAWS glossary that can sweep away the entire snowpack are therefore relatively rare. The most precarious areas remain north-facing slopes between 2200 and 2500 m.
Weather review for Sunday
Conditions were mostly cloudy overnight to Sunday. In the morning, there was precipitation initially in the south, but also in the west during the day. The snowfall level was around 2400 m. In the northeast conditions remained mostly dry, and sunny at times.
Fresh snow
On the main Alpine ridge and south of there, 5 to 10 cm
Temperature
At midday at 2000 m, around +5 °C in the west, +3 °C in the south and +8 °C in the east
Wind
Often moderate from southerly directions
Weather forecast to Monday
During the night and on Monday, there will be repeated episodes of precipitation, sometimes in the form of thunderstorms. The snowfall level will initially be around 2200 m and will drop to 1800 m in the north on Monday.
Fresh snow
From Sunday evening to Monday evening above approximately 2400 m:
- northern and extreme west of Lower Valais, Vaud Alps and from the Avers to the Bernina region: 20 to 40 cm
- elsewhere a widespread 10 to 20 cm
Temperature
At midday at 2000 m, between +5 °C in the southwest and +1 °C in the northeast
Wind
- During the night mostly moderate southwesterly
- Increasing to strong westerly over the course of the day
Outlook
Tuesday
Until Tuesday morning, the north will see widespread precipitation, which will be heaviest on the northern Alpine ridge with 20 to 30 cm. The snowfall level will fall from 1800 m to around 1200 m. During the day the south and Valais will be mostly sunny, while elsewhere it will often remain cloudy. The wind will be a strong, locally storm-force westerly to northwesterly, easing in the afternoon.
The danger of dry avalanches will increase over a wide area. In addition, with the sunshine over the course of the day the fresh snow is expected to produce loose snow avalanches and wet snow slides.
Wednesday
Overnight to Wednesday there will be cloudy intervals. During the day, there will be many cloudy spells, interspersed with sunny intervals. Winds will be light to moderate from westerly directions.
The danger of dry avalanches will decrease. In Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary, however, caution will still be required. The danger of wet avalanches will increase as the day progresses.