Goldberg Group Central

Snowdrift accumulations and persistent weak layer at high altitudes

Snowdrift accumulations and persistent weak layer at high altitudes

Avalanche danger above 2500m is MODERATE, below that altitude danger is LOW. Main danger: weak layers in upper part of snowpack. Danger zones occur seldom but are not visible to the naked eye. Triggering a slab avalanche in these weak lyers is possible esp. on very steep (>35°) slopes. Avalanches can be unleashed even by the weight of one person and grow to dangerously large size. Particularly unfavorable: sunny slopes above 2800 m. Fresh snowdrift accumulations are prone to triggering in isolated places at high altitudes. Danger zones lie esp. in ridgeline terrain and summit zones, usually easy to recognize. Avalanche are mostly small, in regions of the Tauern where snowfall has been heaviest also medium-sized. Circumvent snowdrifts on very steep (>35°) slopes, esp. above concavities in the terrain, e.g. steep fall-endangered slopes. In case of solar radiation, small loose-snow avalanches can be expected on extremely steep (>40°) sunny slopes, also small glide-snow avalanches in places were the ground was previously bare of snow are possible.

By Sunday morning a total of 10-20cm of fresh snowfall, locally up to 30 cm has fallen. Due to fresh snow and NW winds, fresh snowdrift accumulations were generated, were deposited atop a loose snowpack at high altitudes, prone to triggering. On sunny slopes the snowdrift accumulations are unlikely to trigger. Above 2500 m there are expansively metamorphosed (faceted) layers bordering on melt-freeze crusts in the upper part of the snowpack. Reports speak of SE/S/SW slopes above 2800 m being particularly prone to triggering. Weak layers more deeply embedded inside the snowpack are unlikely to trigger. Below 1800 m there is little snow on the ground.

On Monday, sunshine will dominate, visibility will be good. Low lying clouds and fog in early morning or residual clouds can disturb. As evening approaches, high-altitude cirrus clouds from the west will move in. Winds will be mostly light at all altitudes. At 2000 m: -6 to +2 degrees; at 3000 m: -10 to -4 degrees.

Snowdrift accumulations will consolidate, then will be unlikely to trigger. Persistent weak layer at high altitudes will continue to be a threat.