The surface of the snowpack has been influenced by rain, wind and the sun. On the northern flank of the Alps and in Valais,
northern Ticino and large parts of Grisons, a crust has formed on the surface up to altitudes of 2600 to 3000 m. In particular
north of a line between the Rhone and Rhine, the crust is strong in many cases and partly icy.
Above approximately 2600 m, the storm force westerly wind will give rise to small snow drift accumulations that in some instances
are prone to triggering. Below this altitude, only the small quantity of fresh snow can be transported.
On the northern flank of the Alps, slab avalanches are unlikely to be released in deeper layers. From central Valais through
northern Ticino to Grisons, faceted and loosely bonded layers exist in the snowpack. These are lying either directly underneath
the rain crust that formed at the end of December, or they are embedded deeper in the snowpack. At elevated altitudes, these
weak layers remain prone to triggering in some instances.