südliches Urseren

Considerable avalanche danger will be encountered over a wide area.

The new snow and wind slabs of the last few days are in some cases prone to triggering. Single winter sport participants can release avalanches. In some places avalanches can be released in the weakly bonded old snow and reach large size. Whumpfing sounds can indicate the danger. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger.

As a consequence of the rain gliding avalanches and moist snow slides are possible. This applies in particular below approximately 2200 m.

Snowpack The fresh snow and wind slab layers of recent days, which in many cases are deep, are still prone to triggering in some instances. On shady slopes they are settling and bonding only slowly. On Wednesday a strong westerly wind will give rise to snow drift accumulations in particular adjacent to ridgelines. In addition, in all regions, in particular on west, north and east facing slopes above approximately 2200 m, weakly bonded, faceted layers that are prone to triggering exist within the snowpack. In the extreme west of Lower Valais and on the northern Alpine ridge, these weak layers are mostly embedded deep in many places. Here, in particular still in areas where the snow cover is shallow, avalanches can be released in these weak layers of old snow. In particular in southern Upper Valais, northern Ticino and Grisons, these weak layers are closer to the surface and can therefore be released easily in some cases. As a consequence of warming and rain, moist snow slides and gliding avalanches can occur on Wednesday below approximately 2200 m. Observed weather review Tuesday, 28.03.2023 Monday night was cloudy in the east, and snow fell even at low altitudes. Apart from residual cloud in the east, it was initially quite sunny during the daytime. As the day progressed, high-altitude cloudbanks built up from the northwest. Fresh snow In the period from Monday evening until Tuesday morning, 10 to 20 cm of snow fell on the northern flank of the Alps and in northern Grisons, and 20 to 40 cm fell in the northeast. From the onset of the precipitation on Sunday morning until Tuesday morning, the following aggregate amounts of snow fell above approximately 1800 m:

• Extreme west of Lower Valais, northern Alpine ridge, northern Prättigau, Silvretta: 40 to 70 cm; up to 100 cm in the Central Swiss and Glarus Alps
• Rest of the northern flank of the Alps, rest of Valais excluding the southern Simplon region, rest of the Gotthard region, rest of northern Grisons, northern Lower Engadine excluding Silvretta: 20 to 50 cm
• Southern Simplon region, northern Ticino excluding the Gotthard region, eastern part of the main Alpine ridge and neighbouring regions to the north: 10 to 20 cm
• Further south: a few centimetres or none

In the Jura, 10 to 25 cm of snow fell above approximately 1400 m. Temperature At midday at 2000 m: between -2 °C in the west and -6 °C in the east, and about 0 °C in the south Wind From northerly directions

• During Monday night at elevated altitudes and in the south, moderate to strong
• Easing during the day and becoming light to moderate

Weather forecast through Wednesday, 29.03.2023 The north will be mostly cloudy and a little precipitation will fall at times. The snowfall level will rise to 1200 m during the night and to approximately 2200 m during the day. South of the main Alpine ridge it will be mostly sunny. Fresh snow From Tuesday evening until Wednesday afternoon above 2400 m:

• In the north up to 10 cm; from the eastern Bernese Alps into the Glarus Alps locally 15 cm
• Dry in the south

Temperature Increasing, at midday at 2000 m reaching between +4 °C in the west and +1 °C in the east; the zero degree level will rise to 2800 m in the afternoon Wind At elevated altitudes moderate to strong from westerly directions Outlook through Friday, 31.03.2023 Thursday In the north there will be variable to dense cloud with showery precipitation and isolated sunny intervals. The snowfall level will be approximately 1800 to 2200 m. The south will be partly sunny at first before becoming increasingly cloudy as the day progresses. The wind will be moderate to strong from westerly directions. The danger of dry avalanches will decrease slowly. As a consequence of rain, further wet snow and gliding avalanches can occur. Friday It will be frequently cloudy and precipitation will fall at times; in the west the precipitation will be persistent. The snowfall level will drop from 2500 m to approximately 1500 m. The westerly wind will be strong to storm force in the north and at elevated altitudes. The danger of dry avalanches will increase, in particular in the west. The danger of wet snow avalanches will decrease gradually as the temperature falls during the day.