Considerable avalanche danger will be encountered over a wide area
Edition: 22.3.2021, 17:00 / Next update: 23.3.2021, 18:00
Snowpack
The strong wind from northerly directions has transported large quantities of the loosely bonded snow that was lying in many locations. At high altitudes in particular, sometimes large snow drift accumulations have formed; these can be released easily. As the strong wind eases during Monday night, the period of snow transport will end.
Last week’s fresh snow and wind slab layers are lying on a weak layer close to the old snow surface. On the northern flank of the Alps this weak layer is embedded deep and no longer likely to release avalanches. In Valais and Grisons, it is nearer the surface and prone to fracturing on north and east facing slopes in particular, but also on west facing slopes in some instances. In this transitional boundary between layers, several avalanches, in some cases dangerously large ones, have been triggered by people in recent days. In particular in places with shallow snow cover, individual avalanches have penetrated near-ground layers of old snow in their track.
Observed weather on Monday, 22.03.2021
Sunday night in the north was predominantly very cloudy with light snowfall in the east in particular. The south was mostly clear. During the day it became increasingly sunny from the west, including at high altitudes as the upper cloud limit dropped. The south was mostly sunny.
Fresh snow
From Sunday afternoon until Monday afternoon down to low altitudes:
  • Prättigau: 5 to 10 cm
  • Central and eastern parts of the northern flank of the Alps, rest of northern and central Grisons: up to 5 cm
  • Elsewhere: smaller amounts or none
Temperature
At midday at 2000 m: between -2 °C in southern Valais and western Ticino, and -6 °C in the east
Wind
  • Jura, western Prealps: moderate bise
  • Otherwise at elevated altitudes, moderate to strong northeasterly, occasionally storm force on the northern Alpine ridge and the main Alpine ridge
Weather forecast through Tuesday, 23.03.2021
On Monday night the amount of cloud will continue to decrease, including in the northeast. During the day it will be mostly sunny in Valais, and predominantly sunny in the east and south.
Fresh snow
-
Temperature
Increasing; at midday at 2000 m: between 0 °C in the west, -3 °C in the south and -5 °C in the east
Wind
From northerly directions
  • Easing during the night
  • Light to moderate during the day
Outlook through Thursday, 25.03.2021
On each of the two days it will be sunny. On Thursday, high-altitude cloudbanks will pass over during the day and convective cloud will build up. The zero degree level will rise to approximately 2000 m, and a little higher in the west on Wednesday. At elevated altitudes the wind will be light to moderate, initially from the north, then from the west.
The danger of dry avalanches will decrease slowly. The danger of wet snow and gliding avalanches will vary slightly during the day.