Bernese Oberland
Brienz-Interlaken
Day Risk Profile
Avalanche Problems
Wind slab + Persistent weak layers
2=
Field notes
Wind slab
Look for fresh snow deposits on Slope facing downwind/ wind sheltered aspect. Snow deposits can attain several times average snow depth.EAWS glossary, in Usually a steep, elongated, eroded trench; typically prone to snowdrift accumulation.EAWS glossary and Rounded or elongated concavity; typically tending to accumulate snowdrift.EAWS glossary, and behind ridgelines and abrupt changes in terrain — these are where the wind has loaded the snow into slabs that are easy to trigger. Recent avalanches, shooting cracks under your weight, 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 are clear confirmations of the problem. The safest move is to avoid wind-loaded terrain entirely. NB wind signs alone don't always mean an avalanche problem exists, and the age of drifted snow is hard to judge.
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.
Snowpack & Weather
Snowpack
Snow deposited on the ground in a multiplicity of layers.EAWS glossary structure is unfavourable in many locations in southern Valais, Ticino and Grisons, with distinct 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 middle and lower part of the snowpack that are prone to triggering. Reports of 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 avalanches triggered by human activity, often from a distance, continue to be received from these regions. Snowpack structure is somewhat more favourable on the northern flank of the Alps and in northern Valais, but there are weak layers deeper in the snowpack in these regions too. These may still be triggered, especially where there is little snow and at transitions from a deep to shallow snowpack.
Weather review for Sunday
It was very cloudy in the Sotto Ceneri and a little snow fell above approximately 1400 m. Otherwise, it was quite sunny in many locations in the mountains. As the day progressed, thicker clouds moved in from the west.
Fresh snow
In the Sotto Ceneri, locally 5 to 10 cm above approximately 1400 m
Temperature
At midday at 2000 m, around -2 °C
Wind
Moderate southeasterly winds at times on the Northern Alpine Ridge, otherwise mostly light
Weather forecast to Monday
In the south, it will be mostly cloudy and a little snow may fall above approximately 1400 m. In the north, conditions will be mostly sunny in the mountains.
Fresh snow
A few centimetres may fall in the south
Temperature
At midday at 2000 m, between -2 °C in the north and -4 °C in the south
Wind
Mostly light
Outlook for Tuesday and Wednesday
On Tuesday, precipitation and increasing westerly winds will set in from the west. The snowfall level will be around 1500 m. By Tuesday evening, the avalanche danger will increase slightly with small amounts of fresh snow, especially in the west.
During the night to Wednesday, precipitation will intensify, especially in the west and north. The snowfall level will increase to between 1800 and 2000 m. On Wednesday, 30 to 50 cm of new fallen snow is expected in Valais and on the northern flank of the Alps, and up to 80 cm in the far west. There, the avalanche danger will increase rapidly and significantly. Appreciably less snow will fall in Ticino and Grisons. However, due to the weak Snow deposited on the ground in a multiplicity of layers.EAWS glossary, an increase in avalanche danger is also to be expected in these regions.