Waadtländer Voralpen

Considerable avalanche danger will be encountered over a wide area

Considerable avalanche danger will be encountered over a wide area

As a consequence of a strong westerly wind, wind slabs will form. The fresh and older wind slabs represent the main danger. In the course of the day they will increase in size. At elevated altitudes the prevalence and size of the avalanche prone locations will increase. Apart from the danger of being buried, restraint should be exercised as well in view of the danger of avalanches sweeping people along and giving rise to falls.

The frequently deep layers of fresh fallen snow and freshly generated snowdrift accumulations from this week lie deposited atop a pronounced weak layer on west-facing, north-facing and east-facing slopes. From the southern Valais over the northern Ticino as far as Grisons, furthermore, the entire old snowpack is expansively metamorphosed in numerous places. Avalanche triggerings by persons are still easily possible in all regions with the exception of the southern flank of the Alps. This applies in particular to the inneralpine regions. As a result of the small amount of fresh snowfall and westerly winds, predominantly small-sized snowdrift accumulations were generated in the western and the northern regions. These will continue to expand during the course of the day on Sunday as a consequence of increasingly intense winds.

On Friday night in the northern and the eastern regions there was a small amount of fresh snow registered. The snowfall level descended from 1300 down to 600 m. Following dispersal of residual clouds on Saturday it became increasingly sunny during the daytime. In the Jura region, in the Valais and in the southern regions it was generally sunny. Fresh snow: Between Friday evening and Saturday morning the following amounts of fresh snow were registered above approximately 1400 m: - Prealps, northern flank of the Alps from the eastern Bernese Alps as far as Liechtenstein, northern Grisons: 5 to 10 cm, in the eastern sector of the northern flank of the Alps as much as 15 cm; - in the other regions of Switzerland, only a few centimetres; further to the south it remained dry. Temperature: At midday at 2000 m: between -6 °C in the northern regions and -1 °C in the southern regions. Wind: Winds on Friday night were blowing predominantly at moderate strength, at strong velocity in the Jura region and in general at high altitudes, at light to moderate strength during the daytime, from westerly to northwesterly directions. In the Jura region skies will be predominantly overcast. In the Alps it will be quite sunny to start with, cloud cover will move in increasingly from the northwest during the course of the daytime. In the southern regions it will be quite sunny, accompanied by cloudbanks. The westerly winds will intensify noticeably during the course of the day. Fresh snow: - Temperature: At midday at 2000 m: -3 °C in the northern regions and 0 °C in the southern regions. Wind: Winds will be westerly to southwesterly, - blowing at light to moderate strength on Saturday night and in general south of the Main Alpine Ridge; - blowing at moderate to strong velocity during the course of the day, intensifying to strong-to-storm velocity in the northern and the western regions during the course of the afternoon.

Monday: On Sunday night, intensive precipitation will set in, accompanied by storm-strength westerly to northwesterly winds. The snowfall level will lie at 1000 to 1200 m to begin with. During the daytime on Monday the snowfall level will descend down to low lying zones over widespread areas. Only in the furthermost southern regions is it expected to remain dry and partly sunny. On the northern Alpine Ridge, 30 to 50 cm of fresh snow is anticipated. As a consequence of the storm-strength winds the snowfall will extend over into the inneralpine regions; in the Valais, northern Ticino, northern and central Grisons and the Lower Engadine, 20 to 30 cm of new snow is possible. Both fresh fallen snow and old snow will be intensively transported, then distributed and deposited irregularly. The avalanche danger levels are expected to increase significantly over widespread areas. Tuesday: The precipitation will come to an end on Monday evening, the winds will slacken off. On Tuesday it will be generally sunny and significantly milder. The danger of naturally triggered avalanches will decrease. For winter sports enthusiasts in outlying terrain away from secured public ski pistes the situation continues to be critical. During the course of the day on steep sunny slopes, the danger of moist slides from the fresh snow and of gliding avalanches will increase somewhat.