Vaud Alps
Aigle-Leysin
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
By Tuesday evening, snowdrift accumulations that are sometimes prone to triggering will have developed at high altitudes on the main Alpine ridge. These will be medium-sized on the main Alpine ridge in Valais while further east they will still mostly be small.
Over the often cloudy night into Tuesday, the surface of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary will barely freeze, even at high altitudes. Despite the slight decrease in temperature, wet avalanches remain possible, especially on north-facing slopes between 2200 and 2600 m, where the snowpack is becoming saturated for the first time.
Weather review for Monday
The night into Monday was mostly cloudy and outgoing longwave radiation was low. Skies were mostly cloudy during the day. In Valais, a little snow fell above approximately 2300 m. In the east, there were sometimes extended bright spells.
Fresh snow
Five to 10 cm on the main Alpine ridge in Valais above approximately 2300 m and a few centimetres locally in the rest of Valais
Temperature
At midday at 2000 m, between +9 °C in the north and +6 °C in the south
Wind
Moderate to strong from the south
Weather forecast to Tuesday
Conditions will be mostly cloudy on the main Alpine ridge and south of there. Snow will fall at times above approximately 2000 m. Otherwise, conditions will be variably cloudy with extended bright spells in central Valais and those regions exposed to the foehn wind in central and eastern Switzerland.
Fresh snow
From Monday afternoon until Tuesday afternoon above approximately 2500 m:
- main Alpine ridge in Valais: 15 to 25 cm
- Aletsch region, main Alpine ridge from the Nufenen Pass to the Bernina region and south of there: 5 to 10 cm
Temperature
At midday at 2000 m, between +7 °C in the north and +2 °C in the south
Wind
Southerly
- strong at times overnight
- during the day, moderate to strong in the east, moderate in the west
Outlook to Thursday
On Wednesday and into the night to Thursday, there will be frequent precipitation. The snowfall level will initially be at 2000 m, dropping to 1800 m as the snowfall comes to an end. On Thursday, it will initially still be cloudy in the east and south, and very sunny in the west. Over the course of the day, alongside brighter spells, there is a possibility of cumulus clouds and isolated showers in all regions. On Wednesday, there will be sometimes strong southerly winds at high altitudes; elsewhere winds will be mostly light to moderate from the southwest. By Thursday night, 30 to 50 cm of snow is expected from eastern Ticino to the Bernina region and to the south of there above approximately 2500 m. In the Glarus Alps, in the Gotthard region and in central Grisons, up to 30 cm of fresh snow is expected with up to 20 cm falling in other regions.
There will be a widespread increase in the danger of dry avalanches in high altitudes, the danger rising significantly on Wednesday on the main Alpine ridge from eastern Ticino to the Bernina region. On Thursday, the avalanche situation will remain critical for snow sport participants, especially at high altitudes in those regions exposed to heavier precipitation. In all regions, there is still a possibility of isolated wet avalanches being triggered in deep layers of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary, especially on north-facing slopes between 2200 and 2600 m.