Churfirsten and Rhine Valley
Flumserberg
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.
Wet snow + Gliding snow
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Field notes
Wet snow
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.
Gliding snow
Almost impossible to predict precisely, even when the warning signs are visible. A crack visible on the snowpack surface formed by snow-gliding on steep, and particularly grass-covered slopes. Areas below slopes with visible glide cracks should be avoided whenever possible due to threat of gliding sluffs or avalanches.EAWS glossary — gaps that open in the Snow deposited on the ground in a multiplicity of layers.EAWS glossary down to the ground — are often precursors to release, but they don't tell you when. A glide avalanche can release minutes after the cracks appear, or weeks later, or not at all. Some release without any visible warning. Avoid lingering anywhere near glide cracks: above them, alongside them, or below in the runout.
Snowpack & Weather
Snowpack
North of a line from the Rhône to the Rhine and in the extreme west of Lower Valais, 2 to 3.5 m of snow have fallen over the last two weeks. As a result, 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 below are thickly covered and can only rarely be triggered by human activity. However, avalanches may become very large.
South of a line from the Rhône to the Rhine, the 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 that have persisted since the beginning of January are still pronounced. During the night, a Layer of hard-compacted snow resulting from a melt-freeze process or wind.EAWS glossary forms on the surface of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary in many places. The snowpack appears more stable as a result and danger signs such as cracks or 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 become less frequent. However, the low-lying weak layers still exist and avalanches can still be triggered by human activity and become large. In Grisons, avalanche-prone locations are still common. In southern Valais, the significant weak layers in the lower part of the snowpack are mostly rather more thickly covered. Avalanche-prone locations where avalanches can be triggered in the weak Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary are therefore less frequent and mainly located in areas with relatively little snow.
With the rise in temperature through the day, the likelihood of dry 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 being triggered increases slightly during the day. In addition, gliding avalanches are to be expected on steep grassy slopes and wet avalanches on sunny slopes.
Weather review for Wednesday
After a clear night, conditions were sunny and very mild in the mountains.
Fresh snow
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Temperature
At midday at 2000 m, between +8 °C in the north and +5 °C in the south
Wind
Light
Weather forecast to Thursday
After a clear night, it will be sunny and will continue to be mild with a zero-degree level at around 3000 m.
Fresh snow
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Temperature
At midday at 2000 m, around +5 °C
Wind
Light
Outlook to Saturday
Clear nights will be followed by sunny days. On Saturday, clouds will gather from the west in the afternoon. It will remain mild, with the zero-degree level at just under 3000 m on Friday and around 2500 m on Saturday. The wind will be light and at times moderate from the west.
The danger of dry avalanches will continue to decrease, but only very slowly in southern Valais, Ticino and Grisons due to the 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. Gliding avalanches are still to be expected, as well as wet avalanches on sunny slopes. These may become large in the west and north.