Pays d'Enhaut

Increase in danger of dry avalanches

Increase in danger of dry avalanches

At elevated altitudes mostly small wind slabs will form. This applies in particular adjacent to ridgelines and in pass areas. The number and size of avalanche prone locations will increase as the day progresses. In the afternoon possibly danger level 2 (moderate) will be reached. Snow sport participants can release avalanches in isolated cases. They are rather small. Apart from the danger of being buried, restraint should be exercised in particular in view of the danger of avalanches sweeping people along and giving rise to falls.

After a lengthy period of dryness, a several-day period of snowfall was launched on Wednesday. The fresh snow blankets in many places a raw old snow surface and is generally well bonded with it. As a consequence of fresh snow and winds, predominantly small-sized snowdrift accumulations will be generated on Thursday in ridgeline and pass areas in particular. The old snowpack on north-facing slopes below approximately 1800 m, on east-facing slopes below approximately 2500 m, on south-facing slopes up to over 3000 m, and on west-facing slopes below approximately 2800 m, is thoroughly wet. As a result of the dropping temperatures the danger of wet-snow avalanches will decrease. Isolated gliding avalanches are still possible, in particular on the northern Alpine Ridge. Prior to the current snowfall in the northern regions on north-facing slopes above approximately 1000 to 1400 m, in southern regions above approximately 1800 to 2200 m, there was an area-wide coherent snowpack. On south-facing slopes the snowlines lay mostly 300 to 500 m higher up. Over widespread areas there is significantly less snow on the ground than is normal for this juncture of the season, in the southern regions extraordinarly much less snow on the ground. As a result of the thin, often expansively metamorphosed (faceted) snowpack there continues to be heightened danger of falling into crevices on the glaciers, in particular in the southern Valais.

On Tuesday night in the western regions, light precipitation set in. During the daytime hours on Wednesday, skies were heavily overcast and intermittently there was light precipitation. The snowfall level lay at 1400 to 1700 m. Fresh snow: By Wednesday afternoon above approximately 1800 m, there was a few centimetres of fresh snow registered over widespread areas, in the Lower Valais and in the Ticino as much as 10 cm from place to place. Temperature: At midday at 2000 m in the northern regions, 0 °C and in the southern regions -2 °C. Wind: Winds were blowing at light to moderate strength from southerly to southwesterly directions. Skies will be heavily overcast. During Wednesday night, a small amount of precipitation is anticipated over widespread areas, above approximately 1500 m as snowfall. During the daytime hours on Thursday there is precipitation anticipated in the western and the northern regions more than anywhere else. The snowfall level will descend in the afternoon to approximately 1200 m. In the southern regions, northerly winds will create bright intervals in the afternoon. Fresh snow: Between Wednesday afternoon and Thursday afternoon above approximately 1800 m, the following amounts of fresh snow are anticipated - western and central sectors of the northern flank of the Alps, Valais: 10 to 15 cm; - eastern sector of the northern flank of the Alps: 5 to 10 cm; - Grisons, Ticino, and Jura regions: only a few centimetres. Temperature: At midday at 2000 m in the northern regions, -2 °C, and in the southern regions 0 °C. Wind: Winds during Wednesday night will be blowing predominantly at light strength, brisker during the daytime hours on Thursday, mostly at moderate strength, from westerly to northwesterly directions.

Skies will be heavily overcast for the most part, in the mountains frequent precipitation is anticipated, in northern regions the precipitation will be heavy. In the regions south of the Main Alpine Ridge, only little precipitation is expected. The snowfall level will descend down to low lying areas. Between Thursday and Saturday afternoon in the Valais, on the northern flank of the Alps and in Grisons, 20 to 40 cm of fresh snow is expected over widespread areas; on the northern flank of the Alps as much as 60 cm of fresh snow from place to place is possible. The forecasted amounts of precipitation are still uncertain. On Saturday in the southern regions, it is expected to be partly sunny. Winds will shift from westerly to northerly to easterly and be blowing predominantly at moderate strength, in the southern regions intermittently at strong velocity. The danger of dry-snow avalanches is expected to increase on Friday over widespread areas, presumably to Danger Level 3 (considerable) on the northern flank of the Alps and in the Lower Valais. On Saturday, avalanche danger levels could increase somewhat more still from place to place. Avalanches are triggerable mostly in the layers of fresh fallen snow and newly generated snowdrift accumulations.