Upper Valais
Turtmanntal
Manageable day. Moderate, with wind slab and wet snow at the surface — the evidence is there to read before you commit to a slope.
Day Risk Profile
Avalanche Problems
Wind slab
2-
Field notes
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.
Wet snow
2-
Field notes
Rolling snowballs, deep penetration when you step or ski, and small natural slides are clear signals that the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is losing strength. After a clear, cold night the surface often freezes into a strong supporting Layer of hard-compacted snow resulting from a melt-freeze process or wind.EAWS glossary, and conditions are favourable in the early morning. After a warm, overcast night, the problem may be present from the start of the day. Plan early returns and watch the runout zones below you.
Snowpack & Weather
Snowpack
Moisture penetration into the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is well advanced. The most precarious areas are slopes where 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 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. In many places, south-facing slopes are snow-free up to around 3000 m; where there is still snow, moisture penetration extends as far as the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary.
In Grisons, wet The 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 occasionally be triggered by human activity in the weak Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary. At altitudes where the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is still dry, 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 old snowpack are still present, but are unlikely to be triggered anymore.
With the rain, the danger of wet avalanches is elevated even in the late morning.
Weather review for Tuesday
The night was partly clear in the north and overcast in the south. There were showers during the night and in the late morning, mainly in the south, and increasingly in all regions in the afternoon. The snowfall level was between 2200 and 2600 m.
Fresh snow
From Monday evening to Tuesday afternoon in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary:
- Main Alpine Ridge from Val Bregaglia to the Bernina region: 5 to 15 cm
- elsewhere less or dry
Temperature
At midday at 2000 m, around +6 °C
Wind
Light to moderate southwesterly
Weather forecast to Wednesday
The night will be overcast with bright spells. There will be some widespread precipitation until the late morning. During the day it will be cloudy with showers and bright spells in the afternoon, mainly in the west. The snowfall level will be between 2200 and 2600 m.
Fresh snow
In the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary, a widespread 5 bis 15 cm
Temperature
At midday at 2000 m, between +7 °C in the west and +4 °C in the east
Wind
Mostly light; moderate westerly wind for a time during the night in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary, moderate Bise wind in the Prealps during the day
Outlook to Friday
In the north, the nights into Thursday and Friday will be mostly clear and it will be quite sunny during both days. In the south, the nights will often be overcast. It will be only partly sunny during the day on Thursday, and quite sunny on Friday. Winds will mainly be light. The zero-degree level will be around 3000 m. The danger of dry avalanches will decrease rapidly again in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. With sunshine and warming temperatures during the day, the danger of wet avalanches will increase as each day progresses, increasing faster in the south after an overcast night.