Lower Valais
Haut Val de Bagnes
Avalanche Problems
Wind slab
2-
Field notes
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.
Wet snow
2-
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
Saturation of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is well advanced. The most precarious areas are slopes where 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 becoming wet for the first time. As the weather becomes wetter, this is mainly affecting north-facing slopes between approximately 2200 and 2600 m, but in isolated cases also east- and west-facing slopes between approximately 2500 and 3000 m. Many steep south-facing slopes are snow-free up to around 3000 m and where there is still snow, it is saturated to the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. Over the often cloudy night into Monday, the surface of the snowpack will barely freeze, even at high altitudes.
Small snowdrift accumulations will form at high altitudes on the main Alpine ridge in Valais.
Weather review for Sunday
The night was partly cloudy, resulting in a reduction in outgoing longwave radiation. During the day, there were brighter spells in the west, while conditions were very sunny in the east.
Fresh snow
-
Temperature
At midday at 2000 m, between a mild +10 °C in the north and +7 °C in the south
Wind
- Moderate southerly wind
- A foehn wind will rise in the valleys of the north.
Weather forecast to Monday
There will be extended sunny spells in the regions exposed to the foehn wind in the north. Conditions will be very cloudy elsewhere. There will be precipitation on the main Alpine ridge in Valais, falling as snow above approximately 2300 m.
Fresh snow
Main Alpine ridge in Valais: 5 to 10 cm
Temperature
At midday at 2000 m, between +7 °C in the north and +4 °C in the south
Wind
Southerly winds will increase and during the day will be:
- moderate in the west and south, and strong elsewhere;
- and there will be a strong foehn wind in the valleys of the north.
Outlook to Wednesday
On Tuesday, the foehn wind means there will be even longer clear spells on the central and eastern parts of the northern flank of the Alps and in northern Grisons. Elsewhere, conditions will be mostly cloudy with precipitation, most notably on Wednesday in the south. Overall, there will be a widespread 10 to 20 cm of fresh snow, and approximately 30 to 40 cm are expected on the main Alpine ridge from the Nufenen Pass to the Bernina. The snowfall level will drop from 2300 m to 2000 m.
The danger of dry avalanches will increase at high altitudes in many areas, appreciably so on Wednesday on the main Alpine ridge from the Nufenen Pass to the Bernina. Wet avalanches are still to be expected, especially on north facing slopes between 2200 and 2600 m.