Lower Tauern South

Snowdrift problem

Snowdrift problem

Storm-strength winds, fresh fallen snow, rising temperatures on Tuesday afternoon/evening have deposited compact snowdrift accumulations in gullies, bowls and leeward terrain. This applies to heights above the timberline, with snowdrifts becoming more easily triggerable with ascending altitude. Above about 2000 m even the weight of one single person can trigger a release. Due to windblown terrain and generally rough ground surfaces in the backcountry touring zones, the avalanche prone locations should not be underestimated. Second danger. On very steep grass-covered slopes: in those zones, small-to-medium sized glide-snow avalanches can release.

Prior to 25 November on shady slopes the ground was bare of snow up to 2000 m. Depending on altitude, the snow further up was 30-80 cm deep, with several layers, the most compact was on the upper surface. Weak layers: (1) the uppermost layer atop the loose and cold snow from previous days is prone to triggering; (2) in the Hohe Tauern there is a thin fracturable layer beneath the melt-freeze crust, at least in extended northern aspects up to about 2300 m. Wind-exposed zones are utterly windblown, gullies and bowls above the timberline are often filled to the brim. Over warm and smooth ground surfaces, the snowpack is gliding.

Wednesday will start out with heavy cloud, here and there a bit of snowfall is possible as skies brighten (snowfall level at 1400 m). Soon, dry weather will set in, for a few hours some sunshine is expected. At high altitudes a brisk westerly to southerly wind will be blowing, foehn wind blowing at 40-50 km/hr directly on the Main Alpine Ridge. At 2000 m: +1 degree; at 3000 m: -3 degrees.

On Friday the danger of slab avalanches from triggering snowdrifts will diminish somewhat, but moderate gliding snow activity will persist.