Churfirsten and Rhine Valley
Appenzeller Alpen
Day Risk Profile
Avalanche Problems
New snow
3-
Field notes
Easy to spot - the snow is fresh. Look at recent avalanche activity in similar terrain, and pay attention to how much new snow has fallen in the last three days. Critical loading depends on temperature, wind, and what was on the surface before the storm. SLF advises waiting until the Snow deposited on the ground in a multiplicity of layers.EAWS glossary has had time to bond before committing to steep terrain in fresh snow.
Gliding snow
2
Field notes
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
The large volumes of fresh and drifted snow from the last few days and weeks remains prone to triggering in many places.
North of a line from the Rhone 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 are thickly covered and are now barely triggerable by human activity. However, avalanches can occasionally propagate into deep layers, becoming very large as a result.
South of the line from the Rhone 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 are still pronounced. The weakly bonded old snow is most prone to triggering in Ticino and Grisons, where Locations delineated by aspect or altitude where avalanches can trigger and people or objects are at risk.EAWS glossary are still common, 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 and remote triggering are typical, even around the treeline. In southern Valais, the significant weak layers in the lower part of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary are mostly rather more thickly covered. Avalanche prone locations where avalanches can 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 are therefore somewhat rarer and are mainly located in areas with thinner snow cover.
With the mild temperatures, medium to large gliding avalanches are increasingly to be expected on steep grassy slopes below approximately 2000 m.
Weather review for Saturday
There was widespread precipitation in the north and east, which was heavy during the day. In the far south conditions were sunny. The snowfall level rose from 1100 m to around 1500 m.
Fresh snow
From Friday afternoon to Saturday afternoon, above 1600 m:
- eastern part of the northern flank of the Alps: 30 to 40 cm
- Aletsch region, Goms, central part of the northern flank of the Alps, northern Grisons, northern Lower Engadine: 20 to 30 cm
- rest of the northern flank of the Alps, rest of Gotthard area: 10 to 20 cm
- elsewhere a widespread 5 to 10 cm; dry in the far south
Temperature
At midday at 2000 m, between -2 °C in the north and +2 °C in the south
Wind
Moderate to strong northwesterly
Weather forecast to Sunday
Precipitation will continue to fall in the east during the first half of the night. The snowfall level will be around 1500 m and may rise further in some regions towards the end of the precipitation. During the day, all regions will see at least sunny intervals with high broken cloud.
Fresh snow
From Saturday afternoon to Sunday morning above 1800 m:
- eastern part of the northern flank of the Alps, northern Grisons, northern Lower Engadine: 10 to 20 cm
- central part of the northern flank of the Alps, rest of Grisons: 5 to 10 cm; elsewhere less or dry.
Temperature
Rising, at midday at 2000 m between +2 °C in the north and +4 °C in the south
Wind
- Moderate to strong northwesterly during the first half of the night in the south and generally at high altitudes, then easing
- During the day often moderate westerly, sometimes strong in the north in the afternoon
Outlook to Tuesday
On Monday, a further 5 to 15 cm of snow will fall in the north and east above approximately 1600 m. There will be sunny intervals in the west, with the south being mostly sunny. The wind will be a moderate northwesterly, sometimes strong in the south at high altitudes.
Overnight to Tuesday, the far east will see a further few centimetres of snowfall. During the day conditions will be sunny in the west and south, with only sunny intervals towards the east. Temperatures will become appreciably milder. The zero-degree level will rise to 3000 m in the west over the course of the day.
Avalanche danger will 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. With the rising temperatures, more gliding avalanches are to be expected, which may become large in the west and north due to the large amounts of snow.