Upper Engadine and Silvretta
Val Suot
Day Risk Profile
Avalanche Problems
Wind slab + Persistent weak layers
3=
Field notes
Wind slab
Look for fresh snow deposits on Slope facing downwind/ wind sheltered aspect. Snow deposits can attain several times average snow depth.EAWS glossary, in Usually a steep, elongated, eroded trench; typically prone to snowdrift accumulation.EAWS glossary and Rounded or elongated concavity; typically tending to accumulate snowdrift.EAWS glossary, and behind ridgelines and abrupt changes in terrain — these are where the wind has loaded the snow into slabs that are easy to trigger. Recent avalanches, shooting cracks under your weight, and 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 are clear confirmations of the problem. The safest move is to avoid wind-loaded terrain entirely. NB wind signs alone don't always mean an avalanche problem exists, and the age of drifted snow is hard to judge.
Persistent weak layers
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
On wind-protected shady slopes, the fresh snow from the weekend is lying on Transparent, 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 some places. In addition, the loose fresh snow was transported by strong winds from different directions and snowdrift accumulations have formed that are prone to triggering.
In the inneralpine regions of Valais and Grisons, these layers of fresh and drifted snow are also lying on a weak Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary with 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 near the ground. Avalanches can sometimes propagate into these deep weak layers or be triggered directly in these layers in isolated cases. In the other regions, there are still weak layers in the near-ground old snowpack in some places on shady slopes. However, the weak layers are mostly so thickly covered here that they are hardly prone to triggering.
Weather review for Monday
The night was partly cloudy. During the day, it was quite sunny in the south and often cloudy in the north.
Fresh snow
A few centimetres locally
Temperature
At midday at 2000 m, around -3 °C in the north and 0 °C in the south
Wind
- In the north, mostly moderate from southwest to northwest
- In the south, increasingly strong northerly wind in the afternoon
Weather forecast to Tuesday
During the night into Tuesday, there will be some precipitation in the east. The snowfall level will be around 1000 m. It will be sunny in all regions during the day.
Fresh snow
From Monday afternoon to Tuesday morning above approximately 1500 m:
- eastern part of the northern flank of the Alps, northern Grisons: around 5 cm
- elsewhere less or dry
Temperature
At midday at 2000 m, between +2 °C in the west and -2 °C in the east
Wind
- Moderate to strong northerly wind at high altitudes
- During the night into Tuesday, strong northerly foehn wind in the Alpine valleys of the south
- Moderate Bise wind in the Jura
Outlook to Thursday
On Wednesday and Thursday, it will be mostly sunny after a clear night. During the night into Wednesday, there will be strong winds from the northeast to southeast at high altitudes. Otherwise, the wind will be mostly moderate from the northeast to east. Around midday on both days, the zero-degree level will be around 2200 m in the north and 1800 m in the south.
The danger of dry avalanches will decrease. With the solar radiation and the daytime warming, the danger of wet avalanches will increase somewhat over the course of the day.