Bulletin d’avalanche

Heed snowdrifts in shady, steep ridgeline terrain

Heed snowdrifts in shady, steep ridgeline terrain

The snowdrift accumulations of the last few days are still prone to triggering and can be triggered even by the weight of one sole skier in places. Avalanche prone locations occur in shady, steep ridgeline terrain and behind protruberances, as well as in transitions from shallow to deep snow above approximately 2200m. The layers of drifts are generally covered, making them difficult to recognize. In high alpine regions the danger zones are more frequent. In sunny, steep terrain small naturally triggered avalanches can trigger. Due to solar radiation and daytime warmth, glide-snow avalanches are possible below about 2000 m, particularly on steep sunny slopes.

Nighttime skies were generally star-studded and not quite as cold as yesterday. Due to nocturnal outgoing longwave radiation a thin melt-freeze crust formed on steep south-facing slopes which are generally not capable of bearing loads. On shady NE/N/NW slopes there is still loose snow, mostly unbonded. Older snowdrift accumulations are often still prone to triggering, covered and thus, hard to spot. Particularly on shady and east-facing slopes at high altitudes, these are poorly bonded with the old snowpack. Inside the old snowpack on high altitude shady slopes there are still weak layers. In the interim these are well covered and unlikely to trigger. At intermediate altitudes the snowpack is moist, which enhances the gliding movement of the entire snowpack over very steep grass-covered slopes.

Good weather but not as perfect: high altitude clouds will move through, become heavy this afternoon, impede the sunshine somewhat. The peaks will remain free of cloud. Temperature at 2000 m: -1 degree. Light to moderate N/NW winds at high altitude.

The weather forecast promises sunny, pleasant weather all week long. This will lead to the snowpack consolidating gradually. The danger of dry-snow avalanches will incrementally recede.