Central Prealps
Gersau
Stable day. Low, with wet snow and gliding snow named together — one of them visible at the surface, the other buried.
Day Risk Profile
Avalanche Problems
Wet snow + Gliding snow
1
Field notes
Wet snow
Rolling snowballs, deep penetration when you step or ski, and small natural slides are clear signals that the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is losing strength. After a clear, cold night the surface often freezes into a strong supporting Layer of hard-compacted snow resulting from a melt-freeze process or wind.EAWS glossary, and conditions are favourable in the early morning. After a warm, overcast night, the problem may be present from the start of the day. Plan early returns and watch the runout zones below you.
Gliding snow
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
Saturation of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is well advanced. The most precarious areas are slopes where 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 are becoming wet for the first time. As the weather becomes wetter, this is mainly affecting north-facing slopes between approximately 2200 and 2600 m, but in isolated cases also east- and west-facing slopes between approximately 2500 and 3000 m. Many steep south-facing slopes are snow-free up to around 3000 m and where there is still snow, it is saturated to the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary.
Over the often cloudy night into Sunday, the surface of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary will barely freeze, even at high altitudes.
Weather review for Saturday
The night was very clear, the day mostly sunny.
Fresh snow
-
Temperature
At midday at 2000 m a mild +10 °C
Wind
Mainly light
Weather forecast to Sunday
Overnight to Sunday, it will be mostly cloudy in the west, with patchy cloud in the south and east. A foehn wind from the south will pick up over the course of the day. In the west and south, it will be cloudy with some bright spells, and isolated showers are possible in the afternoon. In the east, it will be mostly sunny.
Fresh snow
-
Temperature
At midday at 2000 m, between +8 °C in the north and +5 °C in the south
Wind
Over the course of the day, moderate southerly with a foehn wind in the valleys of the north
Outlook
Monday
Conditions will be cloudy, with bright spells in the east. There will be some precipitation on the main Alpine ridge over the course of the day, falling as snow above approximately 2300 m. There will be a moderate to strong southerly wind, with a foehn wind in the valleys of the north.
The danger of dry avalanches will increase slightly in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary on the main Alpine ridge in Valais. Due to reduced outgoing longwave radiation overnight, there will be a possibility of wet avalanches, especially on north-facing slopes, from the morning onwards.
Tuesday
After a partly clear night, conditions will often be cloudy during the day and snow will fall above approximately 2300 m, most heavily in the south with around 10 cm. In the northeast, conditions will be very sunny and dry. The southwesterly wind will gradually subside.
The danger of dry avalanches will increase slightly in the south and west. Especially in the northeast, there is a possibility of wet avalanches on north-facing slopes as the day progresses.