Central Grisons and Anterior Rhine
Domleschg - Lenzerheide
Day Risk Profile
Avalanche Problems
Persistent weak layers
3-
Field notes
Persistent 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 very challenging to recognise. Distinctive noise (resembling a “whumpf” sound) occurring when a weak layer beneath a slab collapses. The air of the weak layer is forced outside the snowpack, with the resulting whumpf sound being heard. The sound usually indicates an unstable situation and can be accompanied by surface cracking. A whumpf is a clear avalanche alert.EAWS glossary sounds and shooting cracks are typical when present, but you can have a serious weak layer with no warning signs at the surface. Knowledge of how the Snow deposited on the ground in a multiplicity of layers.EAWS glossary has evolved is essential. SLF's travel advice is direct: travel conservatively, avoid terrain where the consequences of being caught are large, and treat the history of weather and snow as more important than what you can see today. Read the full bulletin.
Snowpack & Weather
Snowpack
New snow and drifted snow from the past week is lying on pronounced 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, especially on wind-protected shady slopes. South of a line from the Rhône to the Rhine, the entire Snow deposited on the ground in a multiplicity of layers.EAWS glossary is often faceted and loose. In addition, with the strong southerly winds at times, some highly visible, prone-to-triggering wind slabs have formed over the past three days. On the southern flank of the Alps, the fresh snow from Friday and Saturday was deposited on top of an equally weak snowpack.
It is possible for medium and large-sized avalanches to be triggered in the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary over a wide area. The Snow deposited on the ground in a multiplicity of layers.EAWS glossary on northern and eastern slopes in Valais and northern Grisons is particularly prone to triggering. Avalanches may also be triggered in the old snowpack on the northern flank of the Alps. Remote triggering, sometimes over long distances, is still possible.
Weather review for Sunday
It was mostly cloudy in the west and south. On the southern flank of the Alps, snow fell at times above approximately 1400 m. In the north and east, it was quite sunny with foehn winds.
Fresh snow
From Saturday afternoon to Sunday afternoon, the following amounts of snow fell above approximately 1500 m:
- Great St. Bernard, western Ticino, southern Simplon region: 5 to 10 cm
- Rest of the Main Alpine Ridge and south of this: a few centimetres;
Temperature
At midday at 2000 m, between +3 °C in the north and -2 °C in the south
Wind
From south-east to south
- Moderate to strong in the north, strong foehn wind at times in the regions exposed to the foehn wind in the north
- Mostly light south of the Main Alpine Ridge
Weather forecast to Monday
In Ticino and southern Grisons, it will be mostly overcast with some snow at times. Elsewhere it will be mostly sunny.
Fresh snow
Southern Simplon region, Ticino and southern Grisons: up to 5 cm
Temperature
At midday at 2000 m, around 0 °C in the north and -4 °C in the south
Wind
Moderate to strong southerly foehn wind in the north, elsewhere light to moderate
Outlook to Wednesday
On Tuesday it will still be partly cloudy but dry in the south, and mainly sunny elsewhere. It will be sunny everywhere in the mountains on Wednesday. The southerly wind will slowly subside.
The avalanche danger will continue to decrease but only slowly. 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 Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary will remain prone to triggering, especially in the inneralpine regions.