Northern Lepontine Alps

Fresh wind slabs represent the main danger.

Fresh wind slabs represent the main danger.

20 to 40 cm of snow, and even more in some localities, has fallen since Sunday above approximately 1600 m. Since Monday the wind has been strong. The clearly visible wind slabs of the last two days can be released by a single winter sport participant in particular on west to north to east facing aspects above the tree line. On wind-loaded slopes the avalanches can be triggered in the various wind slab layers and reach large size. Caution is to be exercised in particular at transitions from a shallow to a deep snowpack, as well as in gullies and bowls, and behind abrupt changes in the terrain at intermediate and high altitudes. In the afternoon the likelihood of dry and moist avalanches being released will increase gradually in particular on very steep sunny slopes.

As a consequence of a strong northeasterly wind, sometimes deep wind slabs formed since Monday in particular in areas not adjacent to ridgelines. In addition soft wind slabs formed also in places that are protected from the wind. They are quite prevalent but are difficult to recognise. Outgoing longwave radiation during the night was good. Low and intermediate altitudes as well as steep sunny slopes: The surface of the snowpack has frozen to form a strong crust will soften during the day. Adjacent to ridgelines in high Alpine regions snow depths vary greatly, depending on the infuence of the wind. Transitions from a shallow to a deep snowpack: Various wind slab layers are lying on a hard crust.

Thursday: As a consequence of warming during the day and the solar radiation, the likelihood of moist and wet avalanches being released will increase a little on very steep sunny slopes. This also applies at the base of rock walls.