Nock Mountains

Windslab snow and weak old snowpack with low snow cover

Windslab snow and weak old snowpack with low snow cover

The avalanche risk is moderate above 1800 metres and low below. Slab avalanches can be triggered in some places by small additional loads, but remain predominantly small. Avalanche prone locations increase rapidly above the tree line, at higher altitudes increasingly also in south-eastern aspects. Whumpfing collapsing sounds when stepping on the snowpack can indicate danger. During daytime changes, there is a low risk of small loose snow avalanches on sunny slopes. Terrain traps are less full due to lack of snow and therefore more effective.

The local snow surface varies greatly. There are areas with little snow next to considerable snowdrift accumulations. In windless, shady areas, there is surface hoar on the snowpack, but outgoing longwave radiation is somewhat reduced. A melt-freeze crust usually forms overnight, which softens up to high altitudes on the sunny slopes during the daytime changes. In addition, fresh wind slab begins to build up and is partially slightly soaked on the surface with sunlight, but is often also hard as a board. Where an old snowpack is present, there are faceted crystals on and under the crust at the transition to it, which can serve as a reactive weak layer. Fractures in the persistent weak layer usually occur here. Deeper in the old snowpack there is a sequence of faceted crystals, crusts and a lot of deep rime. The total snow depth is well below average.

The night will be clear for the time being, with widespread clouds moving through from midnight, which will frequently affect the sunshine on Friday. Mountains will remain partly clear. The wind will pick up during the day and blow moderately to strongly from predominantly southerly directions. At 2000 metres the temperature will be -5 to 0 degrees Celsius, at 3000 metres around -7 degrees Celsius.

As the wind dies down, the danger within the stage decreases.