Bernese Oberland
Engstligen
Hard-to-read day. Deteriorating: moderate this morning, considerable by afternoon, with persistent weak layers, wet snow and gliding snow in play — only half of it will be visible.
Day Risk Profile
Avalanche Problems
Persistent weak layers
2=
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
3
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
The Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary still contains various 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 marked warming since Saturday, the likelihood of 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 in these weak layers has been increasing appreciably over the course of each day. On Saturday and Sunday, natural dry or moist slab avalanches occurred mainly in Grisons and in isolated cases also in southern Valais, predominantly on west-facing slopes, and in isolated cases also on all other exposed slopes above 2200 m. In isolated cases, such avalanches also proved to be triggerable by human activity.
On the northern flank of the Alps, these 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 less pronounced. There, as the temperature warms up during the day, numerous gliding avalanches and loose snow avalanches are primarily to be expected. Due to cloudy nights with reduced outgoing longwave radiation and light precipitation, even in the morning there is a danger of avalanches.
Weather review for Sunday
After a mostly clear night, conditions were mostly sunny during the day.
Fresh snow
-
Temperature
At midday at 2000 m, around +8 °C
Wind
Moderate to strong in the north overnight, elsewhere mostly light to moderate
Weather forecast to Monday
The night will be partly cloudy. There may be a little precipitation in the northeast. The snowfall level will be around 2300 m. It will be mostly sunny during the day. On the eastern part of the northern flank of the Alps patchy cloud will continue into the morning.
Fresh snow
Up to 5 cm above 2600 m on the central and eastern parts of the northern flank of the Alps
Temperature
At midday at 2000 m, between +8 °C in the southwest and +4 °C in the northeast
Wind
Moderate westerly in the north and generally at high altitudes during the night, easing during the day
Outlook to Wednesday
On Tuesday and Wednesday, mostly clear nights will be followed by sunny daytime conditions and light winds in all areas. Temperatures will remain very mild, with the zero degree level lying at 3200 to 3400 m.
The danger of dry avalanches will continue to decrease. The danger of wet and gliding avalanches will increase markedly over the course of each day.