Lower Valais
Val d'Anniviers
Hard-to-read day. Moderate, with wind slab and persistent weak layers 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.
Snowpack & Weather
Snowpack
On the northern flank of the Alps, the large volumes of fresh and drifted snow from the most recent period of precipitation are continuing to stabilize. This new and drifted snow is lying on faceted 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, especially on shady slopes, and avalanches can still be triggered in these weak layers, especially in areas with less snowcover. These avalanches may become large in isolated cases.
In the inneralpine regions of Valais and especially Grisons, 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 middle of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary are additionally still prone to triggering in some places, with avalanches possibly starting even in near-ground weak layers in isolated cases.
As temperatures continue to rise, gliding avalanche activity is increasing, for the time being primarily at middle altitudes on the northern flank of the Alps.
Weather review for Thursday
Conditions were mostly clear overnight to Thursday, with some cloudy intervals on the eastern part of the northern flank of the Alps and in Grisons. During the day, conditions were mostly sunny in the west and south, with the east seeing only occasional sun.
Fresh snow
-
Temperature
At midday at 2000 m, between -4 °C in the north and +2 °C in the south
Wind
Moderate to strong northeasterly
Weather forecast to Friday
Overnight to Friday, conditions will be mostly clear in the west and south, with the eastern part of the northern flank of the Alps and Grisons seeing only clear intervals. A little snow may fall in these areas during the night above 1000 m. During the day, it will become increasingly sunny in the east. Elsewhere conditions will be mostly sunny.
Fresh snow
-
Temperature
At midday at 2000 m, between -3 °C in the north and +3 °C in the south
Wind
- Moderate northerly on the northern Alpine ridge, on the main Alpine ridge and on the southern flank of the Alps.
- Elsewhere light
Outlook to Sunday
Overnight to Saturday, there will be cloudy intervals in the north, with some precipitation in the east. The night will be clear on the southern flank of the Alps, and it will be mostly sunny during the daytime. Conditions will be clear overnight to Sunday and it will be mostly sunny during the daytime. The northerly wind will ease overnight to Saturday, becoming mostly light, and will back to westerly on Sunday. Temperatures will become appreciably warmer. On Sunday, the zero-degree level will be at 2800 m.
The danger of dry avalanches will continue to decrease. The danger of wet and gliding avalanches will increase over the course of each day. Tours and hut ascents should be started early and finished in good time.