Bulletin d’avalanche

Solar radiation and high temperatures lead to swift loss of firmness and increasing wet-snow avalanches

Solar radiation and high temperatures lead to swift loss of firmness and increasing wet-snow avalanches

Avalanche danger swiftly rises from low to moderate. Naturally or minimum-artificially triggered moist slides and wet avalanches can be expected especially on E/S/W facing slopes up to high altitudes and on shady slopes below 2200m as temperatures rise during the day. In regions where snowfall has been heavy on very steep grassy slopes, glide-snow avalanches continue to be possible. Backcountry tours should be launched early, brought to an end early. Weak layers in the old snow can still be disturbed at high altitudes in isolated cases. Danger zones occur particularly on very steep shady slopes.

Bonding of recent snowdrift accumulations to the old snowpack is generally good, deteriorates particularly on steep shady slopes with ascending altitude. Small to medium slab avalanches can trigger in the uppermost layers of the snowpack or near the layer of dust from the Sahara. During the mild, partially clear night, a crust formed which sometimes can, sometimes cannot, bear loads. It softens rapidly due to solar radiation and rising daytime temperatures, thereby losing its firmness. The snowpack is disappearing at low and intermediate altitudes.

The air is becoming instable, morning sunshine, only few clouds high above the summits. In the afternoon, convective cloud build-up, some showers are possible. Still warm: the zero-degree level is 3200m. At 2000: 4-9 degrees. Light to moderate SW winds.The air is becoming instable, morning sunshine, only few clouds high above the summits. In the afternoon, convective cloud build-up, some showers are possible. Still warm: the zero-degree level is 3200m. At 2000: 4-9 degrees. Light to moderate SW winds.

Thursday night skies will be overcast, the outgoing longwave radiation reduced. The snowpack has next to no reserves of cold left. Moderate danger of wet-snow and glide-snow avalanches right from the start of the day on Friday.