Monthey-Val d'Illiez · 16 November 2025

Avalanche Problems

Moderate (2-) Dry avalanches · all day

Wind slab 2-

N, NE, E, W, NW

above 2800m

In some regions 10 cm of snow will fall until Sunday above approximately 2400 m. As a consequence of a moderate to strong southwesterly wind, small wind slabs will form in some localities. These are to be evaluated with care and prudence especially in terrain where there is a danger of falling. Apart from the danger of being buried, restraint should be exercised in particular in view of the danger of avalanches sweeping people along and giving rise to falls. The Avalanche Warning Service currently has only a small amount of information that has been collected in the field, so that the avalanche danger should be investigated especially thoroughly in the relevant locality.

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.

Source: SLF Avalanche Bulletin Interpretation Guide

Snowpack & Weather

Snowpack

The snow line on northern slopes is around 2000 m, on southern slopes between 2400 m and 2800 m. At high altitudes, there are patches of continuous Snow deposited on the ground in a multiplicity of layers.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 on shady slopes. The snow depth increases significantly above 2800 m.

The past two weeks have been dry and sunny. While the snow largely melted on steep southern slopes up to high altitudes, the Snow deposited on the ground in a multiplicity of layers.EAWS glossary on shady slopes and in the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary in general began to facet. 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 formed. Avalanches are easily triggered where fresh and drifted snow falls on this snowpack.

Outlook

Monday

There will be widespread precipitation in the north, falling as snow above 1000 m to 1500 m. 20 to 40 cm of snow will fall at high altitudes. The northwesterly wind will be moderate. In the south, it will be partly sunny with moderate northerly winds.

The avalanche danger will increase in the regions exposed to heavier precipitation in the north.

Tuesday

During the night into Tuesday, there will still be a little precipitation above 600 m in the north, with sometimes strong northerly to northeasterly winds. During the day it will be sunny everywhere. The wind will be light to moderate.

Avalanche danger will decrease slowly.

Source

SLF

Issued

15 Nov 15:26 UTC

Valid until

16 Nov 16:00 UTC

Next update

16 Nov 16:00 UTC

Schedule

Off-schedule