Central Prealps
Engelberg
Hard-to-read day. Moderate, with new snow, persistent weak layers and wet snow in play — part of it readable at the surface, part of it buried and silent.
Day Risk Profile
Avalanche Problems
New snow + Persistent weak layers
2+
Field notes
New snow
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.
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.
Wet snow
1
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
The new snow and wind-drifted snow from recent days are still partly prone to triggering, especially on shaded slopes in Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary terrain. At the transition to the underlying Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary, coarse-grained 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 present in some places, particularly on north- and east-facing slopes at higher elevations.
Weather review for Sunday
After a clear night, it was quite sunny with some cumulus clouds
Fresh snow
-
Temperature
At midday at 2000 m, between -1 °C in the north and +4 °C in the south
Wind
Continued moderate winds from the north along the Main Alpine Ridge during the night and mostly light winds during the day
Weather forecast to Monday
The night will be partly clear in the east, and cloudy elsewhere. In the morning there will be continued bright spells, especially in the east. Elsewhere it will often be cloudy with local showers, especially on the northern flank of the Alps. The snowfall level will be around 1800 m.
Fresh snow
A few centimetres locally in the form of showers, especially in the north
Temperature
At midday at 2000 m, between +1 °C in the north and +4 °C in the south
Wind
Often light, occasionally moderate southwesterly at high altitudes in the west
Outlook to Wednesday
Monday night into Tuesday will be partly cloudy in the east and a little snow will fall above 1800 m. In the morning, there will still be residual clouds in the east. Elsewhere, it will be quite sunny at first before clouds move in from the west. In the afternoon, there will be showers in the west, falling as snow above 2200 m. Tuesday night into Wednesday will be clear in the south and often cloudy elsewhere. In central and eastern Switzerland, up to 10 cm of snow will fall above approximately 2200 m. During the day, it will be cloudy with showers in the east. In the west, conditions will be changeable, and in the south it will be quite sunny. There will be a westerly wind on both days, mostly light on Tuesday and moderate at times on Wednesday. The zero-degree level will be at 2500 m on Tuesday, rising towards 2800 m on Wednesday afternoon.
The danger of dry avalanches will decrease. Dry avalanches can still be triggered, primarily on very steep north- and east-facing slopes in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. The danger of wet avalanches will increase slightly as each day progresses. Backcountry ski tours should be completed early.