Chiemgau Alps East

Naturally triggered avalanches possible at high altitudes due to solar radiation and warmth

Naturally triggered avalanches possible at high altitudes due to solar radiation and warmth

Avalanche danger in the Bavarian Alps is considerable above 1400 m, below that altitude danger is moderate. Main problem: fresh fallen snow, massively transported by strong NW winds. Numerous avalanche prone locations are found on steep ridgeline slopes in N/E/SW aspects and in freshly wind-loaded gullies and bowls. Trigger-sensitive snowdrift accumulations occur also behind protruberances distant from ridges and in forest lanes. In these places, even the additional weight of one single skier on the snowpack can trigger a slab avalanche. Frequency and size of the danger zones increase with ascending altitude. As temperatures rise and solar radiation intensifies, the first settling impulses of the fresh snow will lead to naturally triggered, large-sized loose-snow and slab avalanches at high altitudes in particular. Furthermore, inside the old snowpack are trigger-sensitive layers, particularly at high altitudes in transition zones from shallow to deep snow. Superficially triggering avalanches can fracture down to these layers and subsequently grow to far larger size.

Accompanied by stormy westerly winds, there was 20-40 cm of fresh snow registered since yesterday in the Bavarian Alps, as much as 50 cm at high altitudes. Freshly formed wide-ranging snowdrifts have accumulated in which unbonded layers of graupel are embedded. The bonding to the wind crusts and melt-freeze crusts on which they were deposited, or the powder on the old snowpack surface, is poor and prone to triggering. In addition, inside the old snowpack in all aspects are expansively metamorphosed (faceted) crystals near a thin melt-freeze crust. This weak layer is quite pronounced at high altitudes, lying near to the surface or deeper down, depending on wind impact. Below 1400 m the snowpack base is compact and largely stable.

Avalanche danger will recede gradually over the next few days in the stable high-pressure weather conditions.