Considerable avalanche danger will be encountered over a wide area
Edition: 11.5.2021, 17:00 / Next update: 12.5.2021, 18:00
Snowpack
On the main Alpine ridge from the Great St Bernhard Pass to the Bernina Pass and to the south, large quantities of fresh snow and a storm force southerly wind have given rise to extensive snow drift accumulations at elevated altitudes in recent days. These remain prone to triggering in some cases. In the north, fresh snow and wind will give rise to further snow drift accumulations over a wide area.
Below 2500 m, the snowpack has been weakened by heavy rain. With the ending of the precipitation and falling temperatures, the wet avalanche activity will decrease. During Tuesday night, which will be cloudy, the moist surface of the snowpack at intermediate and high altitudes will barely freeze. Individual wet snow and gliding avalanches remain possible.
Observed weather on Tuesday, 11.05.2021
It was very cloudy and precipitation fell over a wide area. On the main Alpine ridge and to the south, there was heavy snowfall at elevated altitudes. During the day the snowfall level dropped from 2500 m to 2200 m. In the afternoon the precipitation eased from the west.
Fresh snow
From the onset of the precipitation on Sunday evening until Tuesday afternoon, the following amounts of snow fell above approximately 2800 m:
  • Main Alpine ridge along the border with Italy from the Simplon region to the Nufenen Pass, Val Bedretto: 80 to 120 cm
  • Rest of northern Ticino, southern Urseren, Zervreila, Rheinwald, Upper Moesano and Val Bregaglia: 50 to 80 cm
  • Rest of the main Alpine ridge from the Great St Bernhard Pass to the Bernina Pass, regions on the northern Alpine ridge from the Jungfrau to the Titlis: 25 to 50 cm
  • Rest of Valais, rest of northern Alpine ridge from the Trient region to the Ringelspitz, rest of central Grisons and Engadine, Val Müstair: 10 to 25 cm
  • Less elsewhere
In central and southern Ticino, equivalent quantities of precipitation fell predominantly as rain.
Temperature
At midday at 2000 m: about +2 °C in the west and +5 °C in the east
Wind
  • During the night, strong to storm force from the south
  • In the morning, moderate to strong from the south, easing further as the day progresses
Weather forecast through Wednesday, 12.05.2021
In the south and in Valais, the snowfall will cease on Tuesday night. In the north, the snowfall will ease from the west during the day. The snowfall level will remain approximately 2000 m during the night, before dropping to 1500 m in the morning. During the day it will be partly sunny in the south, otherwise mostly very cloudy, and isolated showers are possible in the course of the afternoon.
Fresh snow
From Tuesday afternoon until Wednesday afternoon above approximately 2400 m:
  • Northern flank of the Alps from the Jungfrau to the Säntis, Grisons: 15 to 30 cm, but up to 40 cm in northern Grisons
  • Valais and the rest of the western part of the northern flank of the Alps: 5 to 15 cm
  • Elsewhere: a few centimetres
Temperature
At midday at 2000 m: about 0 °C in the north and +4 °C in the south
Wind
  • On Tuesday night in the south, strong from the north; in the northeast, moderate to strong from the northwest
  • Easing during the day, generally light winds in the afternoon
Outlook through Friday, 14.05.2021
On each of the coming days there will be variable cloud with brief sunny spells and, in some regions, showers. On Friday afternoon isolated thunderstorms are also possible. The snowfall level will be approximately 1500 m. The wind will be moderate from the west in the north, and moderate from the north in the south. The avalanche danger will decrease slowly.