Bisistal

Considerable avalanche danger will be encountered in some regions

Considerable avalanche danger will be encountered in some regions

20 to 40 cm of snow has fallen since Thursday. As a consequence of a moderate to strong northeasterly wind, further wind slabs will form in the course of the day. They are to be found in particular in gullies and bowls, and behind abrupt changes in the terrain. Even single snow sport participants can release avalanches, including medium-sized ones. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger and careful route selection. Below approximately 2200 m small to medium-sized gliding avalanches are possible, in particular on very steep sunny slopes. As a consequence of solar radiation moist snow slides are to be expected as the day progresses.

In the northern regions, predominantly small-sized (however in some places trigger-sensitive) snowdrift accumulations have been generated over the last two days as a result of a small amount of fresh snow and winds from varying directions. As a consequence of fresh snow and easterly to northeasterly winds on Saturday, additional relatively small-sized snowdrift accumulations will be generated. From the southern Valais over the northern Ticino and well into the inneralpine regions of Grisons, there are weak layers evident deeply embedded inside the old snowpack. During the course of the last few days, several large-sized avalanches were triggered by persons in the deeper layers of the snowpack in these regions. These avalanche prone locations are not detectable. At high altitudes the snow depths are average over widespread areas for this juncture of the season. Only on the southern flank of the Alps is there extraordinarly little snow, the snow depths remain far-to-very-far below average.

In the northern and the eastern regions, skies were heavily overcast to begin with, accompanied by light snowfall extending down to low lying areas. During the course of the day skies brightened up from the west. In the Jura and the southern regions it was predominantly sunny, in the western regions partly sunny. Fresh snow: Between Thursday evening and Friday midday, the following amounts of fresh snow were registered above approximately 1300 m: - northern flank of the Alps: 5 to 10 cm; east of the Reuss as much as 15 cm; - in the other regions of Switzerland, only a few centimetres; in the Upper Valais and on the southern flank of the Alps it remained dry. Temperature: At midday at 2000 m, -8 °C in the northern regions and -6 °C in the southern regions. Wind: - Winds during the nocturnal hours on Thursday were blowing at strong velocity in the Jura region, in the other regions of Switzerland predominantly at moderate strength, in the southern regions at light strength, from westerly directions; - during the daytime hours blowing at light to moderate strength, in the southern regions at moderate to strong velocity, from northwesterly directions. During the nighttime hours on Friday in the northern regions, showers and a small amount of snowfall is expected down to low lying areas. During the daytime hours in the western and the southern regions it will be predominantly sunny during the course of the day, in the eastern regions increasingly sunny accompanied by convective clouds. Fresh snow: Between Friday evening and Saturday morning, the following amounts of fresh snow are anticipated above approximately 800 m: - central and eastern sectors of the northern flank of the Alps, northern Grisons: 5 to 10 cm; - western sector of the northern flank of the Alps, remaining parts of Grisons: only a few centimetres; in the other regions of Switzerland, it will remain dry. Temperature: At midday at 2000 m, between -4 °C in the western regions and -8 °C in the eastern regions. Wind: Winds will be blowing at moderate to strong velocity from northeasterly directions, in the Jura region and in the western Prealps a moderate-strength bise wind will prevail.

On both days it will be sunny in the mountains, and it will become incrementally milder. The northerly to easterly winds will slacken off during Saturday night. The danger of dry-snow avalanches will decrease. On steep sunny slopes, gliding avalanches continue to be possible.