Middle Lys Valley

The wind slabs must be evaluated with care and prudence. Weak layers in the old snowpack are treacherous.

The wind slabs must be evaluated with care and prudence. Weak layers in the old snowpack are treacherous.

As a consequence of new snow and strong wind the avalanche prone locations will become more prevalent as the day progresses. The fresh wind slabs must be evaluated with care and prudence in particular on north to east to south facing aspects above approximately 2400 m. Single winter sport participants can release avalanches in some places. The avalanches can be triggered in the faceted old snow and reach large size in some cases. Backcountry touring calls for meticulous route selection. Until the temperature drops moist and wet avalanches are to be expected as the day progresses, but they will be mostly small.

10 cm of snow, and even more in some localities, has fallen since Thursday above approximately 2500 m. In the last few days the weather was mild. The rain gave rise to thorough wetting of the old snowpack over a wide area below approximately 2500 m. The old snowpack is unfavourably layered. The snowpack remains weakly bonded on shady slopes. The wind slabs are to be found adjacent to ridgelines and in gullies and bowls. Evening and night: Outgoing longwave radiation during the night will be reduced. The surface of the snowpack will freeze to form a strong crust only at high altitudes.

Above approximately 1500 m snow will fall until Monday. The danger of dry avalanches will increase.