Lower Valais
Val d'Anniviers
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.
Gliding snow
1
Field notes
Almost impossible to predict precisely, even when the warning signs are visible. A crack visible on the snowpack surface formed by snow-gliding on steep, and particularly grass-covered slopes. Areas below slopes with visible glide cracks should be avoided whenever possible due to threat of gliding sluffs or avalanches.EAWS glossary — gaps that open in the Snow deposited on the ground in a multiplicity of layers.EAWS glossary down to the ground — are often precursors to release, but they don't tell you when. A glide avalanche can release minutes after the cracks appear, or weeks later, or not at all. Some release without any visible warning. Avoid lingering anywhere near glide cracks: above them, alongside them, or below in the runout.
Snowpack & Weather
Snowpack
In Lower Valais, northern Valais and the Bernese Oberland, there is as much snow at high altitudes as usual for this time of year, but less in the other regions. There is particularly little snow on the southern flank of the Alps and at intermediate altitudes on the eastern part of the northern flank of the Alps. At 2000 m, there is 30 to 50 cm of snow on the northern flank of the Alps, 10 to 30 cm in southern Lower Valais, northern Upper Valais, the Gotthard region and northern and central Grisons, and less than 10 cm 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 deposited on the ground in a multiplicity of layers.EAWS glossary are located in particular on northern and eastern slopes above approximately 2400 m. Particularly in southern Valais and in some parts of the inneralpine regions of Grisons, human activity can cause these layers to fracture and easily trigger avalanches.
Below approximately 2400 m, the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is moist under the mostly brittle Layer of hard-compacted snow resulting from a melt-freeze process; increases firmness.EAWS glossary; below 2100 m, it is saturated. Isolated wet and gliding avalanches are possible with the sunshine and rising temperatures during the daytime.
Weather review for Thursday
It was cloudy during the night into Thursday and during the day, very cloudy in the east in particular.
Fresh snow
-
Temperature
At midday at 2000 m, between around +4 °C in the north and 0 °C in the south
Wind
Mostly light, moderate at times, initially from the southwest, later from the north
Weather forecast to Friday
The skies will clear during the night. During the day it will be mostly sunny in the mountains with occasional high cloud cover.
Fresh snow
-
Temperature
At midday at 2000 m, around +5 °C
Wind
Mostly light, occasionally moderate from the southwest at high altitudes
Outlook
On Saturday and Sunday it will be mostly sunny and mild with light winds in the mountains.
The danger risk of dry avalanches will slowly decrease. In regions with 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 in particular, human activity can still trigger avalanches in places, possibly large avalanches.
The danger of wet and gliding avalanches will increase slightly during the day with the sunshine and rising temperatures.