Moderate avalanche danger will be encountered in some regions. Weakly bonded old snow requires caution
Edition: 24.12.2021, 17:00 / Next update: 25.12.2021, 18:00
Snowpack
In the lower part of the snowpack, particularly on west-facing, north-facing and east-facing slopes above approximately 2200 m, and on south-facing slopes above approximately 2800 m, weak layers are evident. These layers can still be triggered by persons in some places, particularly from central Valais over the Ticino as far as Grisons. In the furthest western Lower Valais and on the northern flank of the Alps these ground-level layers are covered over by thick layers of fresher snow so that the likelihood of avalanches being triggered by persons is low.
On shady slopes the upper part of the snowpack is expansively metamorphosed (faceted) and loose in many places, and in some places there is surface hoar blanketing the snow cover. This is an unfavourable snow base for the approaching snowfall. On south-facing slopes the snowpack surface shows extensive impact from the sun and is thus more favourable.
As a consequence of westerly winds, small-sized snowdrift accumulations were generated from place to place on Christmas Eve.
Observed weather on Friday, 24.12.2021
On Christmas Eve skies were heavily overcast, but it remained dry for the most part.
Fresh snow
-
Temperature
At midday at 2000 m, +1 °C in the northern regions and -2 °C in the southern regions.
Wind
Winds were moderate to strong in velocity, generally light in the inneralpine regions and the south, from westerly directions.
Weather forecast through Saturday, 25.12.2021
On the night before Christmas in northeastern regions, a small amount of snow is anticipated above 1800 m. On Christmas Day, skies will be predominantly overcast, with extensive bright intervals in the Valais and the southern regions in particular.
Fresh snow
central and eastern sectors of the northern flank of the Alps, northern Prättigau: up to 5 cm.
Temperature
At midday at 2000 m, +1 °C.
Wind
Winds will be blowing at moderate strength, during the night at strong velocity in some places on the northern flank of the Alps, from westerly directions.
Outlook through Monday, 27.12.2021
On Boxing Day and on Monday, skies will be predominantly overcast and intermittent snowfall is expected above approximately 1400 m. In the southern regions and in Grisons, the amounts of new snow will be minor. On the northern flank of the Alps and in the western regions, approximately 5 to 10 cm of new snow is expected each day, although these amounts are still uncertain. Winds will be blowing at moderate strength for the most part, from westerly to southwesterly directions.
Fresh snow and snowdrift accumulations will be deposited on top of an extremely unfavourable old snowpack surface, particularly on shady slopes. The danger of dry-snow avalanches is expected to increase in the northern and western regions. In the southern regions and in Grisons, avalanche danger levels will not change significantly.