Lower Valais
Val d'Hérens
Day Risk Profile
Avalanche Problems
Persistent weak layers
3=
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
With some new snow and westerly winds, snowdrift accumulations that are prone to triggering developed on Friday and during the night to Saturday. They are largest in the west, where the most snow fell.
Snow deposited on the ground in a multiplicity of layers.EAWS glossary structure is unfavourable in many locations in southern Valais, Ticino and Grisons, with 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 snowpack that are prone to triggering. Reports of 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 avalanches triggered by human activity, some from a distance, continue to be received from these regions. Snowpack structure is somewhat more favourable on the northern flank of the Alps and in northern Valais, but there are weak layers deeper in the snowpack in these regions too. These may still be triggered, especially where there is little snow and at transitions from a deep to shallow snowpack.
Weather review for Saturday
A little snow fell in the north during the night. During the day, it was partly sunny in the south and quite sunny in the north.
Fresh snow
From Friday afternoon to Saturday morning above approximately 1400 m, a few centimetres in the north
Temperature
At midday at 2000 m, around -2 °C
Wind
Mostly light
Weather forecast to Sunday
It will be cloudy with bright spells. Most of the sunshine will be in the east in the late morning.
Fresh snow
-
Temperature
At midday at 2000 m, around -2 °C
Wind
Light
Outlook for Monday and Tuesday
On Monday, it will be mostly cloudy in the south and fairly sunny in the north. The avalanche danger will decrease, but only very slowly in Valais, Ticino and Grisons due to the weak Snow deposited on the ground in a multiplicity of layers.EAWS glossary structure. On Tuesday, snowfall and strong westerly winds will set in from the west. Snow will fall to below 1000 m at first, then the snowfall level will rise as the day progresses. The avalanche danger will increase as the day progresses, especially in the west.