Bernese Oberland
Hasliberg - Rosenlaui
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
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 in the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary are still prone to triggering in some places. Weak layers are most widespread in the upper part of the old snowpack. Isolated avalanches can also be triggered in near-ground weak layers, especially on shady slopes that have rarely been used this winter. Locations delineated by aspect or altitude where avalanches can trigger and people or objects are at risk.EAWS glossary for avalanche triggering are most frequently found in Grisons.
Wet and gliding avalanche activity is continuing to increase as temperatures rise.
Weather review for Saturday
The night was mostly clear in the south and often cloudy in the north. Conditions were sunny in the south during the day but elsewhere initially mostly cloudy. There was a little precipitation in the northeast. The snowfall level was between 1500 m and 1800 m. Conditions became increasingly sunny from the west in the afternoon.
Fresh snow
-
Temperature
At midday at 2000 m, between +2 °C in the north and +5 °C in the south
Wind
During the night, moderate to strong northwesterly, subsiding during the day
Weather forecast to Sunday
Dense patches of high cloud will pass through at times during the night. Conditions will be very sunny with high cloud during the day, especially during the afternoon in the north.
Fresh snow
-
Temperature
Rising significantly, reaching around +7 °C at midday at 2000 m
Wind
Mostly light southwesterly, rising to moderate over the course of the day on the northern flank of the Alps
Outlook
Monday
Overnight to Monday, it will often be overcast and there will be a little precipitation in the north. The snowfall level will be around 2200 m. Patchy cloud will persist in the morning in the northeast, but elsewhere conditions will mostly be sunny during the day. Temperatures will remain very mild. During the night, there will be a westerly wind which will be moderate to strong at high altitude but otherwise light to moderate.
The danger of dry avalanches will continue to decrease. The danger of wet and gliding avalanches will already be high in the morning on Monday due to the overcast night and light precipitation and will increase further over the course of the day.
Tuesday
On Tuesday, after a mostly clear night, conditions will be sunny during the day, with very mild temperatures and light winds. The danger of dry avalanches will continue to decrease. The danger of wet and gliding avalanches will increase over the course of the day in the sunshine and rising daytime temperatures.