Vaud Alps
Bex-Villars
Widespread danger. Considerable, with wind slab at the surface — readable, widespread, and unforgiving of a casual line.
Day Risk Profile
Avalanche Problems
Wind slab
3-
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.
Snowpack & Weather
Snowpack
In the north, Tuesday's large volumes of fresh and drifted snow are gradually stabilizing. In some places, however, the fresh snow from recent days is lying on faceted 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 and in some cases also buried Transparent, frequently flat crystals forming on the snowpack when moist air settles on the surface. It forms most often during cold, clear, humid nights. Once it is blanketed by fresh fallen snow, surface hoar is one of the most critical weak layer. See also: www.snowcrystals.itEAWS glossary, particularly on shady slopes. In these weak layers, avalanches can be triggered, which may occasionally become large.
In the inneralpine regions of Valais and especially Grisons, 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 deeper in the Snow deposited on the ground in a multiplicity of layers.EAWS glossary are also still prone to triggering in some places. Isolated avalanches may also be triggered in near-ground weak layers.
Weather review for Wednesday
Conditions were quite sunny in the west and south after a mostly clear night, while the east saw some sunny intervals.
Fresh snow
-
Temperature
At midday at 2000 m, between -8 °C in the north and -4 °C in the south
Wind
Northeasterly
- strong at night, increasing to storm-force at times
- easing to mostly moderate during the day
Weather forecast to Thursday
After a generally clear night, conditions will be quite sunny in the west and south, while the east will see some sunny intervals. Cloud will build up further in the afternoon, but it will remain mostly dry.
Fresh snow
-
Temperature
At midday at 2000 m, around -4 °C in the north and 0 °C in the south
Wind
- Easing overnight to mainly light to moderate northeasterly
- Increasingly moderate northerly during the day, strong in the afternoon on the main Alpine ridge
Outlook to Saturday
In the west and south, the nights will be mostly clear, and conditions will be mostly sunny during the daytime. In the east the nights will be partly cloudy and a few snowflakes may fall locally. Friday will be mostly sunny during the day, and Saturday daytime will see some bright periods. On Friday the wind will continue to be a moderate northerly at times, easing to mostly light on Saturday. The zero degree level will be at 1600 m on Friday in the north and at 2200 m in the south. On Saturday it will rise markedly, to 2800 m in the west and south and to 2400 m in the east.
The danger of dry avalanches will decrease. The danger of wet and gliding avalanches will increase over the course of each day. On Friday, this increase will remain slight but it will be more marked on Saturday. Ski touring should be started early and finished in good time.