Nock Mountains

Heed persistent weak layer in shallow-snow zones of high alpine regions

Heed persistent weak layer in shallow-snow zones of high alpine regions

Above 2000 m, moderate avalanche danger, below that altitude danger is low Main problem: trigger-sensitive intermediate layers at ground-level in the old snow. Isolated slab avalanches can be triggered on shady steep slopes be large additional loading, particularly where the snow is shallow, i.e. at entries to gullies and bowls. Triggered avalanches can be of small-to-medium size. Small, thin snowdrift patches (due to new snow + wind) can lead to slides in steep terrain.

A few centimetres of new snow won’t change anything, even though the melt-freeze crust has a soft layer beneath it. The minor amount of new snow from Monday is too little. In ridgeline terrain, thin snowdrift accumulations can form. Up to 2500 m there is a melt-freeze crust. The recent layers of snowdrifts are relatively well bonded. Potential weak layer of faceted, soft old snow exists as of 2000/2200 m in eastern and northern aspects; there is a moderate to strong tendency towards fracture propagation, especially in shallow-snow and wind-exposed zones.

On Monday, temperatures will plummet, an icy northerly wind (30 km/hr) will be blowing, the summits will be partly in fog in the morning, in the afternoon the clouds will disperse. In some spots, quite sunny. Snowfall from here to there until midday, minor amounts, at most 5 cm, very cold and loose. At 2000 m: -8 degrees; at 3000 m: -12 degrees. On Tuesday, sunshine from morning till night. Cloudless skies. At 2000 m: -8 to -4 degrees; at 3000 m: -9 degrees.. Little or no wind.

Little change