Snowpack

In spite of solar radiation, the weak layers embedded inside the latest rounds of new fallen snow and newly generated snowdrifts which were deposited at high altitudes over the last few days are stabilising only slowly and continue to remain prone to triggering in some places. From place to place, avalanches can sweep away even more deeply ensconced layers inside the snowpack. At heightened altitudes, conditions are wintery for this juncture of the season. There continues to be a great deal of loosely-packed snow evident, which will possibly be transported by the currently arising southwesterly winds.
The old snow cover is thoroughly wet on north-facing slopes below 2500 m, on east-facing, south-facing and west-facing slopes below approximately 3000 m. Wet-snow and gliding avalanches continue to be possible, particularly in case of solar radiation.

Observed weather on Thursday, 20.05.2021

In the southern regions it was predominantly sunny. In the western regions and the Engadine there were some bright intervals. In the central and eastern sectors of the northern flank of the Alps and in northern Grisons, the bright intervals tended to be seldom and showers were registered well into the afternoon.

Fresh snow

The snowfall level lay at approximately 1500 m. At heightened altitudes, the following amounts of fresh snow were registered between Wednesday afternoon and Thursday afternoon:

central and eastern sectors of the northern flank of the Alps: 5 to 15 cm;
Lower Valais, western sector of the northern flank of the Alps, Goms, northern and central Grisons: up to 10 cm from place to place.

Temperature

At midday at 2000 m, between -2 °C in the northern regions and +3 °C in the southern regions.

Wind

Winds were blowing from northerly to northwesterly directions,

predominantly at moderate strength, during the nighttime hours blowing at strong velocity from place to place;
slackening off during the afternoon.

Weather forecast through Friday, 21.05.2021

Following a night of overcast skies on Thursday night, skies in the central and eastern foehn-influenced sectors will be bright in the early morning hours on Friday. Subsequently, skies in the southern regions will become increasingly overcast from the west; and later, precipitation is expected to set in.

Fresh snow

The snowfall level will lie at 2400 m. Above that altitude, a few centimetres of fresh fallen snow is anticipated on the northern flank of the Alps and in the Valais.

Temperature

At midday at 2000 m, +5 °C.

Wind

Winds will be southwesterly,

intensifying, starting on Thursday night;
during the daytime hours on Friday, blowing predominantly at moderate to strong velocity;
blowing at storm-strength in the western regions.

Outlook through Sunday, 23.05.2021

Saturday

On Friday night, snowfall is anticipated over widespread areas. The snowfall level in the northern regions is expected to descend from 2600 m down towards 1600 m, in the southern regions the snowfall level will lie at 2200 m. Most of the precipitation is expected to fall in the furthermost western regions and on the Main Alpine Ridge from Ticino into the Bernina region, where as much as 20 to 40 cm of fresh snow is possible at heightened altitudes. In the morning hours the precipitation will come to an end and some bright intervals are anticipated, accompanied by showers from region to region. The westerly wind will be blowing at moderate strength at high altitudes, in some places at strong velocity.
The danger of dry-snow avalanches is expected to increase once again at heightened altitudes. As a result of solar radiation, numerous moist loose-snow slides and avalanches can be expected to release from the fresh fallen snow.

Sunday

On Whit Monday it is expected to be variably cloudy and partly sunny accompanied by showers in the afternoon in particular.
The danger of dry-snow avalanches will gradually decrease at high altitudes. The danger of wet-snow avalanches will be subject to a slight daytime avalanche-danger cycle.