Western Prealps
Vallée de Joux
Avalanche Problems
Wet snow
1
Field notes
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.
Snowpack & Weather
Snowpack
Snow depths are well above average in the west and north, with more than twice as much snow as usual for this time of year in places. In other regions, there is a widespread 50 to 100% of the usual amount of snow and only 30 to 60% on the southern flank of the Alps.
Deep layers of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary are faceted and weak, especially on shady slopes above approximately 2400 m and generally in Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. In regions with deep snow in the west and north, these 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 now thickly overlaid and are therefore no longer so easily triggered by winter sports participants. However, any avalanches triggered in these deep layers can still become large. In regions with little fresh snow, avalanches are easier to trigger in deep layers of old snow and will usually be of medium size.
Small to medium gliding avalanches are still expected in the west and north.
Weather review for Saturday
Overnight to Saturday, a few centimetres of snow fell in the east above approximately 1500 m. During the day, conditions were sunny in the west and south and increasingly sunny in the east.
Fresh snow
A few centimetres in the east, otherwise dry
Temperature
Around 0°C at midday at 2000 m in the east and +3°C in the west and south
Wind
Mostly light from westerly directions
Weather forecast to Sunday
Clouds will rapidly gather overnight to Sunday. There will be brighter intervals during the day, especially in northern and central Grisons and Lower Engadine. Elsewhere it will be mostly cloudy. In the afternoon, light snowfall will set in in the north-west above approximately 1400 m.
Fresh snow
A few centimetres in the west on Sunday afternoon
Temperature
At midday at 2000 m, around 0°C
Wind
The southwesterly wind will be moderate in the west, otherwise mostly light. In the Jura, there will be a strong westerly wind at times in the afternoon.
Outlook
Around 5 cm of snow will fall in the north overnight to Monday. The snowfall level will drop to 900 m. Some clouds will remain during the day along the Prealps and in the east while conditions will be mostly sunny in the mountains. On Tuesday, conditions will often be cloudy on the southern flank of the Alps but elsewhere mostly sunny. The zero-degree level will be around 2000 m. There will be a light southerly wind on both days.
Avalanche risk will continue to fall. Gliding avalanches are still possible in regions with deep snow in the west and north.