Lower Valais
Arolla
Updated off-schedule
The provider reissued this bulletin at 20 Oct 15:00 UTC, outside the normal publication cycle.
Manageable day. Moderate, with new snow at the surface — the evidence is there to read before you commit to a slope.
Day Risk Profile
Avalanche Problems
New snow
2=
Field notes
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.
Snowpack & Weather
Snowpack
Snow deposited on the ground in a multiplicity of layers.EAWS glossary
Over the past two weeks, some snow fell in the high mountains, with the largest amounts along the main Alpine ridge from the Monte Rosa region to the Bernina region. This snow has partly undergone faceting. Further snowfall is expected on Wednesday. On shady slopes in the high mountains, the fresh snow will fall on a partly continuous Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary. In these areas, fractures may occur at the interface between the old and fresh snow, particularly on glaciers. Elsewhere, the snow will generally fall on bare ground. In these areas, 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 most likely to occur within the fresh snow and wind slabs.
Outlook
Thursday
During the night to Thursday, some precipitation will persist in the north. During the day, it will be mostly sunny, but remain cloudy in the east. The wind will be moderate to strong from the northwest.
The danger of dry avalanches will gradually decrease. Wet loose snow avalanches are to be expected on steep sun-exposed slopes in the high mountains.
Friday
On Friday, it will be variably cloudy with occasional precipitation, especially in the west. In the east, it will remain dry with sunny intervals. The snowfall level will be around 1500 m. The southwesterly wind will strengthen, reaching storm force, with a southerly foehn in the Alpine valleys.
The southwesterly wind may give rise to wind slabs that are prone to triggering. In the high mountains, people can still trigger avalanches, particularly on steep north-facing slopes.