Lower Valais
Montana
Day Risk Profile
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.
Snowpack & Weather
Snowpack
There are 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 in the middle and lower part of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary, particularly on wind-protected shady slopes. These areas are particularly widespread south of a line from the Rhône to the Rhine and on the southern flank of the Alps. In these weak layers, medium-sized and sometimes even large avalanches can still be triggered by human activity. The snowpack on northern and eastern slopes in central Valais, as well as in northern Grisons, is particularly prone to triggering and remote triggering is also still possible in these areas in particular. On the northern flank of the Alps, isolated avalanches triggered in the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary were last reported at the weekend.
Weather review for Wednesday
Conditions were sunny in the mountains.
Fresh snow
-
Temperature
At midday at 2000 m, between +2 °C in the north and -2 °C in the south
Wind
Mostly light southwesterly to westerly winds
Weather forecast to Thursday
Sunny at first. During the course of the day, clouds will move in from the west and become increasingly dense.
Fresh snow
-
Temperature
At midday at 2000 m, between -1 °C in the north and -4 °C in the south
Wind
Mostly light southwesterly to westerly winds
Outlook to Saturday
On Friday, it will be cloudy in the west and south with sunny intervals in the north-east. On Friday afternoon, precipitation will set in on the Main Alpine Ridge and to the south of it, which will continue until Saturday morning. The snowfall level will be at low altitude. There will be hardly any precipitation in other regions. On Saturday, it will be mostly cloudy on the southern flank of the Alps and in southern Grisons. Some precipitation may fall. Otherwise it will be dry with sunny intervals.
The avalanche danger will increase slightly with the fresh snow on the Main Alpine Ridge and south of it, but will hardly change elsewhere. 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 layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary will remain prone to triggering, especially in the inneralpine regions.