Review:
The period of fairly modest snow conditions began on 12.12. and lasted until 5.1.
The warm front, which visited us on 12.12. with light rain up to around 2000-2300m (Tyrol), moistened the snow surface. With the cold temperatures and clear nights that followed, a cover formed on the snow surface. On December 14, a period of fine weather began with clear nights and dry air, during which the snow surface cooled down considerably. On 21 and 22 December, a snow surface temperature of -20°C was measured at the Kühtai Längental measuring station.
Phases of fine weather with clear nights promote the accumulating transformation enormously and the energy exchange with the atmosphere takes place not only at night but also during the day. The drier the air and colder the temperatures, the more the snow surface is cooled. In addition, the wind also cools the snow surface somewhat.
These processes resulted in a large temperature difference in the layers near the surface, which set the process of anabolic transformation in motion. Angular crystals formed again and the snow surface became increasingly loose again on shaded slopes. In areas protected from the wind, a snow surface of loose, angular crystals, also known as nap powder, could be found, usually alternating with broken snow.
In addition, surface frost was formed in many places due to the build-up transformation on the surface (deposition). High fog, which prevailed for several days from December 16, intensified the formation of surface frost and huge frost crystals could sometimes be observed.
On December 29/30, the next warm front hit us. At first it brought snowfall, but as temperatures rose, so did the rain line in some areas up to around 2500m. This was followed by several days with spring-like temperatures that were too warm for this time of year. No wonder that many people got their climbing gear out again to climb a few more pitches on the pleasantly warm rock! The conditions for ski tours deteriorated rapidly due to the rain.
The rain on 29/30 December and the very warm temperatures up to 5 December had one huge advantage, however, as the previously extensive surface frost and loose snow surface was destroyed, at least at low altitudes! If these layers were covered by fresh snow, they would form an extremely toxic weak layer. So at least the conditions in the forest area - even after the fresh snow - remain quite avalanche-safe.
On January 5, the time had come, a cold front brought lots of white flakes!!! Fresh snow at last! What was interesting was that when the snow started to fall, the wind died down briefly and then picked up again. This created different layers in the fresh snow pack, as you can see from the snow profile. Above the tree line, cold drift snow packs formed that are easy to disturb.
