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
In Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary, the last few days’ fresh and drifted snow is lying primarily on steep north-facing slopes on faceted 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 top part of the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary. Avalanche reports from recent days confirm that these weak layers are in some cases prone to triggering.
Further saturation of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is currently progressing only slowly. Avalanche of wet snow masses. Flowing more slowly than dry avalanches; usually for shorter runout distances, however with greater impact on obstacles due to higher snow density.EAWS glossary that can sweep away the entire snowpack are therefore relatively rare. The most critical areas are north-facing slopes between 2200 and 2600 m, where the snowpack is becoming saturated for the first time.
Weather review for Friday
Overnight to Friday saw occasionally cloudy skies. During the day, conditions were often sunny with some cumulus clouds and isolated showers.
Fresh snow
-
Temperature
At midday at 2000 m, around +7 °C
Wind
Light to moderate southwesterly
Weather forecast to Saturday
The night to Saturday will mostly be clear. During the day, conditions will be very sunny with cumulus clouds and isolated showers as the day progresses.
Fresh snow
-
Temperature
At midday at 2000 m, around +7 °C
Wind
Mostly light southwesterly
Outlook to Monday
The night to Sunday will be mostly overcast while, during the day, it will be very cloudy with some precipitation, especially in the south. The snowfall level will be around 2400 m and there will be a moderate southerly wind at times in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. Monday will likewise often be overcast, with some widespread precipitation, which will be heaviest in the west, where 10 to 20 cm of snow is expected at high altitudes. The snowfall level will be around 2200 m, with a moderate to strong westerly wind at high altitudes.
The danger of dry avalanches will not change significantly on Sunday, but will increase somewhat on Monday.
During the overcast nights, there will be little outgoing radiation from the Snow deposited on the ground in a multiplicity of layers.EAWS glossary, meaning the danger of wet avalanches will be subject to little diurnal variation. Due to the relatively cool weather, avalanche activity is expected to remain low.