Engelberg

Fresh snow in the south and the snowdrift accumulations formed by the southerly winds have been deposited on a very weak old snowpackSnow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary. 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 has also formed in many places over the past few days and has now been covered by fresh snowfall in the south. Avalanches can therefore easily be triggered at the transition between the fresh and old snow.

There are distinct 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 middle and lower part of the snowpackSnow deposited on the ground in a multiplicity of layers.EAWS glossary, particularly on wind-protected shady slopes. Such places are particularly common south of a line from the Rhone to the Rhine. In these weak layers, people can still trigger medium-sized and, in isolated cases, large avalanches. The snowpack on northern and eastern slopes in central Valais, as well as in northern Grisons, is most prone to triggering while north of a line from the Rhone to the Rhine, the deeper layers of the snowpack are somewhat less prone to triggering and hazardous zones are less common there.

During the night, some snow fell in the west and south down to low altitudes. During the day, there were sunny intervals in the north, but elsewhere there was mainly heavy cloud cover.

Fresh snow

• On the Main Alpine Ridge and to the south of there as well as in the Jura: 5 to 10 cm
• Elsewhere less or mostly dry

Temperature

At midday at 2000 m, between 0°C in the north and -4°C in the south

Wind

South to southwesterly

• during the night: mostly moderate; strong foehn wind in the north
• during the day: light to moderate

Snow will fall overnight in the south down to low altitudes and skies will remain overcast during the day, while in the north there will be broken cloud with some snow at times.

Fresh snow

From Saturday evening to Sunday lunchtime:

• on the Main Alpine Ridge from Monte Rosa to the Bernina region and to the south of there: 10 to 20 cm
• rest of the Main Alpine Ridge in Valais, rest of the Engadine: 5 to 10 cm
• elsewhere less or mostly dry

Temperature

At midday at 2000 m, around -5°C

Wind

• During the night: moderate to strong from southerly directions, strong foehn wind in the north
• During the day: light to moderate from westerly directions

Monday

In the north, there will be broken to heavy cloud cover with a little snow falling down to low altitudes. In the inneralpine regions, there will be some sunny intervals over the course of the day, while conditions will be mainly sunny on the southern flank of the Alps with moderate northerly winds. There will be light to moderate winds from westerly directions.

There will be no significant change in avalanche risk.

Tuesday

On Tuesday, there will be sunny intervals at first before thicker clouds gather from the west. In the afternoon, there will be intermittent precipitation in the Jura, with the snowfall level rising to around 1500 m. Winds will rise to strong from the southwest, with a strong to storm force foehn wind in the north.

Small snowdrift accumulations will form locally, resulting in a slight increase in avalanche risk.