Waadtländer Voralpen

Moderate avalanche danger will be encountered over a wide area. Wet avalanches during the day.

Only a little snow is lying. Individual wet and gliding avalanches are possible. Mostly these are 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.

Snowpack Fresh fallen snow and freshly generated snowdrift accumulations from the last few days on north-facing slopes above approximately 2500 m lie deposited atop loosely-packed layers. In Grisons the surface hoar was blanketed by fresh fallen snow in many places. The near-surface layers are still prone to triggering in some places on the high-altitude north-facing slopes more than anywhere else. As a consequence of the lower temperatures of the last few days, the process of the snowpack becoming thoroughly wet was brought to a stop. East-facing, south-facing and west-facing slopes were already thoroughly wet up to higher than 3000 m. On north-facing slopes the wetness was halted between 2000 and 2500 m. As a result of increasingly higher temperatures, initially the surface-near layers of the fresh snow and snowdrift masses will become moist, before water seepage into the snowpack will be unleashed and subsequently, more deeply embedded layers will be weakened. At higher altitudes, snow depths on the northern flank of the Alps and in northern Grisons correspond to long-term medium values, in the Valais the snow depths lie slightly above that level over widespread areas. Further to the south, the snow depths continue to lie significantly below the customary values for this juncture of the season. Observed weather review Wednesday, 26.04.2023 In the northeastern regions there was a small amount of snowfall on Tuesday night. Subsequently, skies cleared. In the western and the southern regions, nighttime skies were predominantly clear. During the daytime on Wednesday it was predominantly sunny in general over widespread regions. Fresh snow The snowfall level lay at 1400 m. Between Tuesday afternoon and Wednesday morning the following amounts of fresh snow were registered above approximately 2000 m:

• central and eastern sectors of the northern flank of the Alps, northern Prättigau: 5 to 10 cm;
• in the remaining regions of Switzerland, less; or else it remained dry.

Thus, between Sunday morning and Wednesday morning the following overall amounts of fresh snow were registered above 2500 m:

• furthermost western part of the Lower Valais, northern flank of the Alps: 30 to 50 cm;
• in the remaining regions of Switzerland: 15 to 30 cm over widespread areas, in Grisons somewhat more in some places; in the southern Lower Valais, less.

Temperature At midday at 2000 m, between 0 °C in the northern regions and +3 °C in the southern Valais and in the central sector of the southern flank of the Alps. Wind Winds were blowing from westerly directions,

• during the nocturnal hours on Tuesday, frequently at strong velocity, particularly at high altitudes and in pass areas in the central and eastern sectors of the Main Alpine Ridge;
• slackening off during the course of the day, blowing generally at light to moderate strength.

Weather forecast through Thursday, 27.04.2023 Nighttime skies in northern regions on Wednesday night will be overcast to start with, accompanied by a small amount of precipitation in the northeastern regions, subsequently skies will clear from the west. In the southern regions, nighttime skies will be predominantly clear. During the daytime hours on Wednesday, residual clouds will persist to begin with, particularly in the eastern regions. Later in the day, it will become quite sunny there, accompanied by high-altitude cloudbanks, as was already the case in the remaining regions of Switzerland. In the late afternoon hours, cloud cover will become more dense in the western regions. Fresh snow

• In the central and eastern sectors of the northern flank of the Alps, a few centimetres of fresh snow is anticipated above approximately 1600 m over widespread areas;
• in the other regions of Switzerland it is expected to remain dry.

Temperature At midday at 2000 m, between +7 °C in the Lower Valais and +4 °C in the remaining regions of Switzerland. Wind Winds will be blowing from westerly directions,

• predominantly at light strength;
• intermittently at moderate velocity, particularly at high altitudes during the nocturnal hours on Wednesday.

Outlook through Saturday, 29.04.2023 Friday On Thursday night, skies are expected to be predominantly overcast. During the daytime hours on Friday, it will be partly sunny only on the southern flank of the Alps, in the other regions of Switzerland skies will be heavily overcast. In the northern regions a small amount of precipitation is anticipated on the northern flank of the Alps more than anywhere else. The westerly winds will be blowing at increasingly strong velocity at high altitudes. It will remain mild, with the zero-degree level at 3000 m. The danger of dry-snow avalanches is expected to increase, particularly at high alpine altitudes in the northern regions. At intermediate and high altitudes, it is wet-snow avalanches that are to be expected more than anything else, as a consequence of rainfall, particularly in the central and eastern sectors of the northern flank of the Alps and in northern Grisons. These releases can grow to large size on north-facing slopes in particular. Saturday During the nocturnal hours on Friday the precipitation is expected to come to an end in the northern regions, and skies will clear. In the southern regions the nighttime skies will be predominantly clear. Winds are expected to shift to northerly and then slacken off. Temperatures will continue to be mild. The danger of dry-snow avalanches will remain at heightened levels in high-alpine mountain terrain. The danger of wet-snow avalanches will be subject to a daytime danger cycle.