Upper Engadine and Silvretta
Val dal Spöl
Hard-to-read day. Moderate, with wind slab, persistent weak layers and wet snow in play — part of it readable at the surface, part of it buried and silent.
Day Risk Profile
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.
Wet snow
2+
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
With fresh snow and gale-force westerly winds at times, Monday saw the formation of snowdrift accumulations prone to triggering. On the northern flank of the Alps and in Valais these are continuing to grow, with some becoming large, while otherwise 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 high altitudes.
Where there is sunshine, the fresh snow will make moist snow slides likely on Tuesday.
Weather review for Monday
Conditions were very cloudy with repeated precipitation. The snowfall level was initially around 2500 m but fell to 1800 m in the north in the afternoon.
Fresh snow
From Sunday evening to Monday evening above approximately 2800 m:
- northern and extreme west of Lower Valais, Vaud Alps and from Avers to the Bernina region: 20 to 30 cm
- elsewhere a widespread 5 to 15 cm
Temperature
At midday at 2000 m, around +3 °C
Wind
- Initially mostly moderate southwesterly
- In the afternoon strong at times from westerly directions
Weather forecast to Tuesday
Until Tuesday morning there will be widespread precipitation in the north. The snowfall level will drop from 1800 m to around 1200 m. During the day conditions will be mostly sunny in the south and in Valais. The central and eastern parts of the northern flank of the Alps will see extensive cloud cover until the afternoon, with the possibility of isolated showers.
Fresh snow
From Monday evening to Tuesday midday above approximately 2200 m:
- northern and extreme west of Valais and northern flank of the Alps: 20 to 40 cm
- rest of Valais and northern Grisons: 10 to 20 cm
- less elsewhere; dry in the south
Temperature
At midday at 2000 m, between +1 °C in the southwest and -3 °C in the northeast
Wind
- During the night moderate to strong from westerly directions
- During the day at high altitudes and generally in the south, strong to gale-force northwesterly
Outlook
Wednesday
Overnight to Wednesday there will be cloudy intervals. During the day, it will be very sunny despite patchy cloud. 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 slightly as the day progresses.
Thursday
There will be clear spells overnight to Thursday. During the day there will be patchy to heavy cloud cover, with some precipitation at times. The snowfall level will be between 1400 m in the north and 1800 m in the south. The wind will mostly be a moderate south-westerly, strong at times in the north.
There will be no significant change in dry avalanche danger. Especially in Valais, there will be a possibility of isolated wet avalanches as the day progresses.