Moisture penetration into the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary is well advanced. The most precarious areas are slopes where 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 in the old snowpackSnow 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. At present, this mainly affects north-facing slopes between approximately 2200 and 2500 m, and east- and west-facing slopes between approximately 2500 and 2800 m. On south-facing slopes, moisture penetration into the snowpack extends as far as the high alpine regionsAreas above approximately 3000 m (particularly glaciated areas).EAWS glossary. In Grisons, the weak layers in the old snowpack are the least deeply buried, which means that wet slab avalanchesThe abrupt release of a slab of snow on a mountain slope. After crack initiation and crack propagation in a weak layer the released slab comprises 3 elements: The weak layer, the gliding horizon and the slab. If the slope angle is steep enough, the slab will glide down. If the slope is not steep enough, the slab will settle down on the failed weak layer. Possibly a whumpf sound will follow due to air pressed out of the weak layer. The fracture line will be sharp edged.EAWS glossary can also occasionally be triggered by human activity. In areas higher up, where the snowpack is still dry, weak layers in the old snowpack are still present, but are unlikely to be triggered anymore.

During the night into Tuesday, outgoing longwave radiation will be partially reduced in the inneralpine regions and strongly reduced on the northern flank of the Alps and the central part of the southern flank of the Alps. In addition, it will rain on the central part of the southern flank of the Alps during the night, increasing the danger of wet snow avalanchesAvalanche 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 in this area in particular even in the morning.

After a mostly clear night, it was mostly sunny and mild during the day.

Fresh snow

-

Temperature

At midday at 2000 m, between +10 °C in the west and south and +7 °C in the east

Wind

Light

During the night into Tuesday, high cloud will increase and outgoing longwave radiation will be reduced. Showers are expected in central Ticino and in the Sotto Ceneri. In the morning, there will still be bright spells in Valais and the Engadine; otherwise, it will be variably cloudy with showers, especially in the afternoon. The snowfall level will drop from 2800 m to 2400 m in the south. In the north, it will be around 2300 m.

Fresh snow

A few centimetres in the high alpine regionsAreas above approximately 3000 m (particularly glaciated areas).EAWS glossary

Temperature

At midday at 2000 m, around +7 °C

Wind

Mostly light from southwesterly directions

Wednesday

During the night into Wednesday, bright spells are possible in Valais and on the southern flank of the Alps; otherwise, it will be very cloudy. During the day, it will be variably cloudy with bright spells, especially in the Prealps and in Valais. Showers are still to be expected with a snowfall level of around 2400 m. In the high alpine regionsAreas above approximately 3000 m (particularly glaciated areas).EAWS glossary, 5 to 10 cm of snow is expected to fall. There will be a moderate to strong Bise wind in the Prealps; at high altitudes, the wind will be mostly light. In the high alpine regions, the danger of dry avalanches may increase somewhat. Where there is reduced outgoing longwave radiation during the night and with rain, the danger of wet avalanches will increase even in the early morning.

Thursday

The night into Thursday will be mostly clear in the north, and mostly sunny during the day. On the southern flank of the Alps, the night will be mostly cloudy, turning increasingly sunny during the course of the day. The zero-degree level will be around 3000 m again. In the north, the avalanche situation will be generally favourable in the early morning. The danger of wet snow avalanchesAvalanche 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 will increase as the day progresses. On the southern flank of the Alps, due to the cloud cover during the night, daytime changes in the danger of wet snow avalanches will be less pronounced and the danger will increase even in the early morning.