Lenk

There is less snow than is usual at this time of year in most regions. Only in northern Lower Valais are snow depths about average. On southern slopes and generally below 2400 m, the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary is mostly wet or has frozen solid.

At high altitudes on the Main Alpine Ridge and to the south of there, this week’s fresh snow is lying on a thin but weak old snowpackSnow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary of faceted crystalsSnow grains, solid, with multiple flat glassy faces and sharp edges. Developed from faceting metamorphism, usually poorly bonded to one another (fewer contact points), a critical factor in avalanches if a faceted layer is covered with bonded snow. Typical grain size: 0.5 to 3 mm See also: www.snowcrystals.itEAWS glossary.

Particularly in the inneralpine regions of Valais and throughout Grisons, there are sometimes pronounced weak layersSnowpack 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 of faceted crystalsSnow grains, solid, with multiple flat glassy faces and sharp edges. Developed from faceting metamorphism, usually poorly bonded to one another (fewer contact points), a critical factor in avalanches if a faceted layer is covered with bonded snow. Typical grain size: 0.5 to 3 mm See also: www.snowcrystals.itEAWS glossary or surface hoarTransparent, frequently flat crystals forming on the snowpack when moist air settles on the surface. It forms most often during cold, clear, humid nights. Once it is blanketed by fresh fallen snow, surface hoar is one of the most critical weak layer. See also: www.snowcrystals.itEAWS glossary in the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary, especially on northern and eastern slopes above approximately 2400 m. However, hardly any avalanches have been triggered in these layers for some days.

Further north, the structure of the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary is more favourable.

Despite the strong southerly wind, only small local snowdrift accumulations have formed, as there was hardly any transportable snow left.

Conditions were very sunny in many parts of the mountains of the north. Some snow fell in southern Valais and western Ticino, especially during the night. The snowfall level was around 1500 m.

Fresh snow

From Saturday afternoon to Sunday afternoon, the following amounts of snow fell above approximately 1800 m:

• Main Alpine Ridge of Valais, Bedretto, Upper Valle Maggia: 5 to 10 cm

Temperature

At midday at 2000 m, between +6°C in the north and 0°C in the south

Wind

• Strong southerly winds, moderate in the north, during the day
• Mostly light winds in the south

Cloudy in the south, elsewhere very sunny despite patches of high-altitude cloud. A few snowflakes may fall on the Main Alpine Ridge in Valais.

Fresh snow

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Temperature

At midday at 2000 m, between +4°C in the north and -2°C in the south

Wind

• Moderate to strong southerly winds in the north, easing during the day
• Strong foehn wind during the night and in the morning in the alpine valleys of the north
• Mostly light in the south

A little snow will fall in the south on both days. A total of 5 to 10 cm of snow may fall on the Main Alpine Ridge and south of there. The snowfall level will be around 1500 m on Tuesday and will drop to around 900 m on Wednesday. In the north, conditions will be very sunny in the mountains on Tuesday and there will be sunny intervals on Wednesday, with little likelihood of precipitation.

There will be no significant change in avalanche risk.