Considerable avalanche danger will be encountered over a wide area
Edition: 20.3.2021, 17:00 / Next update: 21.3.2021, 18:00
Snowpack
The fresh fallen snow and freshly generated snowdrifts from the beginning of this week were deposited atop a weak layer adjoining the old snowpack surface. This layer is deeply blanketed over on the northern flank of the Alps and no longer likely to trigger. In the Valais and in Grisons, it is less thickly blanketed over and prone to triggering on west-facing, north-facing and east-facing slopes more than anywhere else. In this transition of layers, several avalanche were triggered by persons during the last few days. Avalanches which fracture down to ground-level layers occurred only in very isolated cases and then, in places where the snowpack was shallow.
As a result of strong-velocity northeasterly winds, loosely-packed snow will be transported. The freshly generated snowdrift accumulations are frequently prone to triggering.
Observed weather on Saturday, 20.03.2021
In the northeastern regions skies were frequently overcast, accompanied by intermittent sunny intervals and snow showers extending down to low lying areas. Elsewhere it was predominantly sunny.
Fresh snow
Eastern Jura region, Prealps, central and eastern sectors of the northern flank of the Alps, northern Grisons: 5 to 10 cm.
Temperature
At midday at 2000 m, between -8 °C in the western regions and -12 °C in the eastern regions, and -6 °C in the southern regions.
Wind
  • in the Jura region, western Prealps: a moderate to strong bise wind was blowing;
  • at heightened altitudes: during the nocturnal hours on Friday night, winds were blowing at light to moderate strength, intensifying during the daytime on Saturday, reaching moderate to strong velocity, from northeasterly directions;
  • in the southern regions: moderate strength northerly foehn wind developed during the course of the day.
Weather forecast through Sunday, 21.03.2021
On Sunday morning in the northern and eastern regions, cloud cover will move in. Starting at midday, a small amount of snowfall is anticipated, extending down to low lying areas. In the northwestern region it will remain sunny for somewhat longer, in the afternoon it will become increasingly overcast. In the southern Valais and on the southern flank of the Alps it will be predominantly sunny.
Fresh snow
Northern flank of the Alps from the eastern Bernese Alps as far as Liechtenstein, northern Grisons, Silvretta, Samnaun: only a few centimetres.
Temperature
At midday at 2000 m, between -4 °C in the southern and southwestern regions and -8 °C in the eastern regions.
Wind
  • in the Jura region, Prealps: a moderate strength bise wind will be blowing;
  • in the other regions of Switzerland: moderate to strong-velocity northerly to northeasterly winds, intermittently strong-to-stormy on the Alpine Ridges.
Outlook through Tuesday, 23.03.2021
Monday
In the northern and the eastern regions skies will be heavily overcast for the most part and by late morning 5 to 10 cm of fresh fallen snow is expected to fall down to low lying regions. During the course of the day in the western sector of the northern flank of the Alps and in general in high alpine regions, it will become increasingly sunny. In the Valais and in the southern regions it will be quite sunny. In the Jura region and the Prealps, a moderate-strength bise wind will be blowing, at high altitudes a strong-velocity northerly wind will prevail. The danger of dry-snow avalanches is not expected to change significantly. The danger of moist-snow avalanches and gliding avalanches will increase somewhat in the western and southern regions on steep sunny slopes more than anywhere else during the course of the day.
Tuesday
In the northern regions it will be sunny above the high fog, accompanied by cloudbanks. In the Valais and in the southern regions it will be predominantly sunny. The zero-degree level is expected to ascend to nearly 2000 m in western regions, in eastern regions to nearly 1500 m.
The danger of dry-snow avalanches will incrementally decrease. The danger of wet-snow and gliding avalanches will increase on steep sunny slopes in the western and southern regions more than anywhere else during the course of the day.