Martigny-Verbier

In the west a high avalanche danger will be encountered in some regions.

The wind slabs of the last few days are lying on the unfavourable surface of an old snowpack. Single winter sport participants can release avalanches. Whumpfing sounds serve as an alarm indicating the danger. Avalanches can in some cases release the entire snowpack and reach medium size. This applies in particular on north facing slopes above approximately 2400 m, as well as on south facing slopes above approximately 2800 m. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger.

Snowpack The often strong wind has transported the fresh snow that has fallen since last weekend. In particular in the eastern part of the northern flank of the Alps and in Grisons, in some localities old snow has been transported as well. Snow drift accumulations that are prone to triggering have formed over a wide area. In the west these accumulations are large. The fresh snow and wind slab layers are settling and bonding only slowly because of the low temperatures. The snow drift accumulations will increase in size a little more on Tuesday night as a consequence of fresh snow and wind. Faceted and loosely bonded weak layers are to be found in deep layers of the snowpack on north facing slopes above 2200 m to 2400 m and on south facing slopes approximately 2800 m. These are prone to triggering in particular in southern Valais and in Grisons. Observed weather review Tuesday, 17.01.2023 On Monday evening more snow than expected fell in western Lower Valais. The snowfall then gradually eased on Monday night. During the day it was very cloudy and, in the west and south in particular, snow fell in showers even at low altitudes. In the northeast it remained dry and, in the afternoon, became increasingly bright. Fresh snow From Monday afternoon until Tuesday afternoon above approximately 1000 m:

• Lower Valais in the extreme west and north: 30 to 50 cm
• Vaud and Fribourg Alps, western Bernese Oberland, rest of Lower Valais: 15 to 30 cm
• Jura, remaining western part of the northern flank of the Alps, northern Upper Valais, southern flank of the Alps, Bernina region: 5 to 10 cm
• Elsewhere: smaller amounts or none

Since Saturday afternoon, the following aggregate amounts of snow have fallen above approximately 2000 m:

• Lower Valais in the extreme west and north: 50 to 70 cm, locally more on the border to France
• Vaud and Fribourg Alps, rest of Lower Valais, western Bernese Alps: 25 to 50 cm
• Rest of the northern flank of the Alps and Upper Valais excluding both the Upper Visp valleys and the southern Simplon region: 15 to 25 cm, smaller amounts elsewhere

Temperature At midday at 2000 m: about -6 °C in the west and about -8 °C in the east and south Wind

• On Monday night in the Prealps and the Jura, moderate to strong, otherwise light to moderate from the southwest
• During the day in the north, mostly moderate; in the south light to moderate from southerly directions
• As the day progressed in the northern regions exposed to the foehn, a moderate to strong foehn wind
• At elevated altitudes in the Jura, moderate from the east

Weather forecast through Wednesday, 18.01.2023 The north will be very cloudy and snow will fall over a wide area, even at low altitudes. The south will be partly sunny. Fresh snow From Tuesday afternoon until Wednesday afternoon the following amounts of snow will fall above 800 m:

• Extreme west of Lower Valais, northern Lower Valais, Vaud Alps: 15 to 25 cm
• Jura, rest of the northern flank of the Alps: 10 to 15 cm, smaller amounts elsewhere

Temperature At 2000 m: about -10 °C in the north and -8 °C in the south Wind

• During Tuesday night in the north, moderate to strong; in the south light to moderate from the southwest to west
• During the day easing a little and veering northwesterly

Outlook through Friday, 20.01.2023 In the north on both days it will be cloudy with bright intervals and local snow showers. In Valais and the south it will be partly sunny on Thursday and quite sunny on Friday. As a consequence of the moderate north to northeasterly wind, it will be very cold in the mountains. The avalanche danger will decrease slowly in the north, but not change significantly in the south.