The snowpack surface shows striking effects from rain, wind and sun. It
is encrusted or even iced over up to altitudes of 2600 to 3000 m on the
northern flank of the Alps, in the Valais, in northern Ticino and in
most parts of Grisons. On steep sunny slopes it softens and slushes up
during the course of the day.
On the northern flank of the Alps, there is little likelihood
of slab avalanches fracturing down to more deeply embedded layers of the
snowpack. From central Valais over the northern Ticino as far as
Grisons, the snowpack is either expansively metamorphosed (faceted) and
loose immediately beneath the surface crust, or else deeper-down layers
are weak and prone to triggering in some places. This applies to
north-facing slopes above approximately 2400 m and south-facing slopes
above approximately 2800 m more than anywhere else.