Middle Lys Valley

Wind slabs and weakly bonded old snow require caution.

Wind slabs and weakly bonded old snow require caution.

The fresh snow from last week, and especially the accumulations of both soft and hard wind-blown snow, cover a thin layer of old snow. Single winter sport participants can release avalanches as before, including medium-sized ones. Mostly they are shallow, caution is to be exercised in particular in gullies and bowls, and behind abrupt changes in the terrain, and on very steep slopes. On very steep shady slopes the avalanches can be triggered in deep layers of the snowpack and reach large size in isolated cases. Slopes that have been little used this winter thus far where weaknesses exist in the old snowpack are especially unfavourable. Isolated whumpfing sounds and shooting cracks when stepping on the snowpack serve as an alarm indicating the danger. Careful route selection and spacing between individuals are recommended. On extremely steep south facing slopes mostly small moist snow slides are possible as the day progresses as a consequence of solar radiation.

As a consequence of new snow and a moderate to strong wind from northwesterly directions, wind slabs formed in the last few days above the tree line. Faceted weak layers exist in the old snowpack in particular on west, north and east facing slopes. Since Thursday, numerous spontaneous and triggered slab avalanches have been observed in areas bordering Switzerland and France.

The wind will be moderate to strong. Some snow will fall in the evening. These meteorological conditions will prevent a change towards better conditions.