Boletín de aludes

Fresh snow + fresh snowdrifts prone to triggering.

Fresh snow + fresh snowdrifts prone to triggering.

The fresh snow and in particular the wide-ranging snowdrift accumulations can be triggered by one single skier in all aspects above 1800 m. Avalanches can grow to medium-to-large size. Avalanche prone locaddtions occur on steep slopes near to and distant from ridges, behind protruberances and in wind-loaded gullies and bowls. Furthermre, naturally triggered medium-sized avalanches are possible on steep sunny slopes due to solar radiation. Activities in backcountry terrain require experience in assessing risks on-site. Weak layers in the old snow can be triggered by one sole skier/boarder, particularly in Rätikon, Silvretta and Verwall on N/NE facing slopes, especially above 2000 m on seldom-frequented backcountry terrain in transitions from shallow to deep snow, e.g. at entries into gullies and bowls. Superficially triggered avalanches can fracture down to deeper layers and then grow to large size. In addition, at intermediate altitudes on smooth, steep grass-covered slopes small-to-medium glide-snow avalanches are possible.

A weak perturbance struck during the night, bringing mostly 2-5 cm of fresh snow, 5 cm in barrier cloud zones of the Arlberg region and Bregenzerwald. Winds were blowing at moderate to strong velocity from W/NW, generating fresh snowdrift accumulations. In the last 24 hours there has been up to 15 cm of fresh snow registered in the barrier cloud zones of the Arlberg, Allgäu Alps and rear Bregenzerwald, elsewhere 5-10 c. on Monday and Tuesday there was massive snow transport by storm winds and snowfall, intermittently with graupel showers. These snowdrift accumulations are still prone to triggering in places, can be triggered with ease. The snowpack shows immense wind impact: exposed zones are hard and windblown, leeward slopes, gullies and bowls are filled to the brim with drifts. In the Rätikon, Verwall and Silvretta the snowpack has weak layers. In those regions avalanches which are triggered can fracture down to these deeper layers and grow to large size. At intermediate altitudes the snowpack is moist, which reinforces gliding movement over smooth slopes.

The day will begin with clouds, fog and light snowfall down to 1300-1100 m. The clouds will disperse in the morning, visibility improve, and by afternoon the sun will come out. This evening, skies will be clear. Temperatures will rise. At 2000 m: -2 to 0 degrees. Initially moderate to strong NW winds, later slackening off.

On Thursday, temporarily better conditions, some foehn wind and measurably milder. On Friday, the next weak perturbance will arrive. Avalanche danger is not expected to change significantly.