At elevated altitudes a considerable avalanche danger will be encountered in some regions
Edition: 22.5.2021, 17:00 / Next update: 23.5.2021, 18:00
Snowpack
In the high alpine regions, conditions continue to remain wintery for this juncture of the season. Strong-velocity, to some extent storm-strength southwesterly winds at heightened altitudes, and in high alpine regions most of all, have transported the loosely-packed snow. As a consequence of the fresh fallen snow and wind, new snowdrift accumulations will be generated on Saturday night. Freshly generated and somewhat older snowdrift accumulations are prone to triggering in some places and can be triggered by persons. As a result of solar radiation, numerous moist-snow slides and avalanches are expected to release from the near-surface layers. In addition, small-to-medium sized wet-snow and gliding avalanches are possible below approximately 2500 m on very steep slopes.
Observed weather on Saturday, 22.05.2021
Following precipitation over widespread areas on Friday night, skies cleared up in the early morning hours on Saturday starting in the west. Subsequently, as a result of convective cloud build-up, it became rather sunny in the western regions, partly sunny in the southern and eastern regions.
Fresh snow
The snowfall level descended from approximately 2200 m down to 1400 m. Between Friday afternoon and Saturday morning, the following amounts of fresh snow were registered above approximately 2500 m:
  • northern Alpine Ridge from Lower Valais into the Gotthard region and Main Alpine Ridge from the Gotthard region into the Bernina region and southwards therefrom: 15 to 30 cm;
  • in the other regions of Switzerland, 5 to 15 cm over widespread areas.
Temperature
At midday at 2000 m, between 0 °C in the northern regions and +3 °C in the southern regions.
Wind
Winds were westerly to southwesterly,
  • blowing at strong-velocity to storm-strength during the nocturnal hours;
  • blowing predominantly at moderate strength at heightened altitudes in particular during the daytime hours.
Weather forecast through Sunday, 23.05.2021
During the night, skies will be heavily overcast accompanied by precipitation over widespread areas. In the early morning hours it is expected to become sunny in the western regions, subsequently increasingly sunny also in the eastern regions, accompanied by convective cloud build-up. In the southern regions, following a night of overcast skies it is expected to be predominantly sunny during the daytime.
Fresh snow
The snowfall level will lie at 1200 to 1500 m. Between Saturday evening and Sunday midday, the following amounts of fresh snow are anticipated:
  • furthermost western part of Lower Valais, northern flank of the Alps, northern Grisons, Engadine and southern valleys of Grisons: 5 to 15 cm;
  • remaining parts of Grisons, central Grisons, Ticino: for the most part less, or else it will remain dry.
Temperature
Temperatures are expected to rise during the daytime: to between +1 °C on the northern flank of the Alps and +5 °C in the southern regions, at midday at 2000 m.
Wind
Winds will be westerly to southwesterly,
  • blowing predominantly at moderate strength at high altitudes;
  • blowing intermittently at strong velocity in the high alpine regions.
Outlook through Tuesday, 25.05.2021
Monday
In the southern regions, skies will be heavily overcast, accompanied by precipitation. In the northern regions, it will be rather sunny to begin with. Subsequently, cloud cover will increase there as well during the course of the day. A moderate-to-strong velocity southwesterly wind will be blowing, in the Alpine valleys of the north there will be foehn wind. The danger of dry-snow avalanches is expected to remain at heightened levels in high alpine regions.
Tuesday
On Monday night, a small amount of precipitation is anticipated over widespread areas. During the daytime on Tuesday it will be dry and partly sunny in the northern regions, in the southern regions as a result of northerly winds, quite sunny. The danger of dry-snow avalanches needs to be evaluated with particular attentiveness on-site in the high alpine regions more than anywhere else.