Goldberg Group North

Snowdrifts atop unfavorable base: prone to triggering

Snowdrifts atop unfavorable base: prone to triggering

The danger is dependent on amount of new snow and wind influence. Above the treeline danger will be CONSIDERABLE, below that altitude MODERATE. Danger zones are found especially where snowdrits cover a soft, loose base, most often the case on wind-protected, shady slopes (also in sparsely wooded zones) and in steep gullies. In exposed terrain at high altitudes, slabs can be triggered from inside the freshly generated drifts. To trigger a medium-sized slab avalanche, even minimum additional loading is sufficient in many places. Poor visibility makes assessing the danger on-site more difficult.

Amid strong wind impact, often major amounts of fresh snow will fall, the base in exposed terrain is often wind-pressed or melt-freeze encrusted (in high alpine regions often wind swirls). On east and south-facing slopes and in gullies there are older drifts from recent days. In protected, shady zones the loose old snow and also the surface hoar is being covered over, these can serve as weak layers. Inside the old snowpack, soft, faceted layers around the melt-freeze crusts further weaken the structuring.

On Friday, persistent snowfall, often moderate-to-heavy. Widespread, 15-30 cm is expected, sometimes 40 cm. Stormy W/NW winds will be blowing. At 2000 m: -9 degrees; at 3000 m: -17 degrees. Saturday will begin dry and partly sunny, with high-altitude clouds the light could become diffuse. Initially hardly any precipitation. Winds will persist at transport strength. Much milder. At 2000 m: rising from -8 to -3 degrees; at 3000 m: from -11 to -6 degrees.

On Saturday, fresh, compact drifts will be deposited. The likelihood of triggering will remain heightened in wind-loaded zones.