Monte Rosa

At elevated altitudes a moderate avalanche danger will prevail.

The fresh snow and local wind slabs are in some cases prone to triggering. Winter sport participants can release avalanches in some places, including medium-sized ones. The prevalence of the avalanche prone locations will increase with altitude. Careful route selection is advisable.

The Avalanche Warning Service currently has only a small amount of information that has been collected in the field, so that the avalanche danger should be investigated especially thoroughly in the relevant locality.

Snowpack For longer than a week there has been fresh snowfall registered every day at heightened altitudes, so that in the high alpine regions a measurable amount of fresh snow has accumulated in the interim. Frequently the snowfall was accompanied by strong-velocity winds, thus, large-sized snowdrift accumulations have been generated. Fresh fallen snow and freshly generated snowdrift accumulations are settling and consolidating to an increasing degree, however in the high alpine regions isolated avalanches have been triggered from near-surface layers of the snow cover by persons during the last few days. Beneath the fresh snow of the last few days, the old snow cover on north-facing slopes below approximately 2700 m, in the other aspects up to over 3000 m, is thoroughly wet. In Grisons more than anywhere else, but also in some parts of the southern Valais and in isolated cases also in the other regions of Switzerland, there are still weakened layers evident deeply embedded inside the snow cover. Avalanches which trigger in the fresh fallen snow and freshly generated snowdrift accumulations can sometimes fracture down to these layers and subsequently plummet down great distances. Observed weather review Thursday, 18.05.2023 In the eastern sector of the northern flank of the Alps and in Grisons, it was sunny to start with, in the remaining regions of Switzerland skies were overcast accompanied by some bright intervals. During the afternoon hours skies were overcast in all regions of Switzerland. Fresh snow - Temperature The zero-degree level at midday lay at 2700 m. Wind During the nocturnal hours on Wednesday, winds were blowing at moderate strength in some places from southeasterly directions, during the daytime hours winds were light. Weather forecast through Friday, 19.05.2023 During the nighttime hours on Thursday skies will be heavily overcast and showerlike precipitation is expected, falling as snow above 2400 m. During the daytime hours on Friday, short sunny intervals are anticipated, during the afternoon the showers are expected to continue, including possible thunderstorms from place to place. In the southern regions, precipitation is expected all day long. Fresh snow Between Thursday afternoon and Friday afternoon, the following amounts of fresh snow are expected above 2600 m:

• Upper Valais sector of the Main Alpine Ridge: 15 to 25 cm;
• remaining parts of the Main Alpine Ridge and Aletsch region: 5 to 15 cm;
• in the other regions of Switzerland, less.

Temperature The zero-degree level at midday will lie at 2600 m. Wind Winds will be light, blowing intermittently at moderate strength, from southeasterly directions. Outlook through Sunday, 21.05.2023 Saturday On the Main Alpine Ridge and in the southern regions, skies are expected to be heavily overcast accompanied by a small amount of fresh snowfall above 2400 m. The largest amounts of snowfall (20 to 40 cm) are expected in the Upper Valais sector of the Main Alpine Ridge from Zermatt as far as the Simplon. In the remaining regions of Switzerland there will be more extensive bright intervals, but also a great deal of convective cloud build-up and, from place to place, showers. The zero-degree level will ascend to over 3000 m. Winds will be blowing predominantly at moderate strength from southeasterly directions. Avalanche danger levels are expected to increase measurably in the Upper Valais sector of the Main Alpine Ridge, in the other regions of Switzerland the avalanche danger levels are not expected to increase significantly. Sunday On Sunday, partly sunny weather is anticipated in the mountains, however isolated showers and/or thunderstorms are also possible. In the Upper Valais sector of the Main Alpine Ridge from Zermatt as far as the Simplon, an additional 20 to 40 cm of snow is expected to fall, so that the danger of dry-snow avalanches will continue to increase in the high alpine regions there. Winds will be blowing intermittently at strong velocity from southeasterly directions. Temperatures are expected to rise further, the zero-degree level will ascend to 3300 m. The danger of dry-snow avalanches, and also of wet-snow avalanches, can continue to increase in the Upper Valais sector of the Main Alpine Ridge. In the remaining regions of Switzerland, the danger levels are not expected to change significantly. As a consequence of higher daytime temperatures and solar radiation, moist-snow avalanches can be expected in all aspects there during the course of the day. Backcountry tours and ascents to mountain refuges should be brought to an end early in the day.