We are in the last few days of Moderate/Low avalanche danger as the weather pattern is finally changing. Warming and flurries begin on Wednesday, but the real change comes over the weekend with 10-20 cm of snow along with warming; +5 in Banff by Saturday. Avalanche danger will begin rising later this week.
Lingering hard wind slabs exist on alpine lee features. Potential failure planes are either old weak facet layers or the Jan 30 layer of facets, sun crusts, and isolated surface hoar beneath the recent snow.
A fresh report just in of a fatal avalanche that occurred south of Golden on Monday. A small windslab on a north aspect at 2300 m carried one person a long way (1000 m) down a steep, confined gully with many terrain obstacles.
No new avalanches were reported or observed in the Banff, Yoho & Kootenay region, but Lake Louise forecasters report many people skiing aggressive lines.
Aging wind slabs sit on top of the Jan 30 interface. Specific areas exposed to the wind may also have strastrugi. The mid-pack is generally weak facets, while depth hoar over a crust forms an even weaker base. The snowpack is the weakest in eastern areas where snow depths are low. In these areas, the basal weaknesses should be carefully considered.
Say goodbye to the Arctic ridge of high pressure deflecting all the weather systems around us. Starting Wednesday, the ridge retreats and the warm-up begins with new snow arriving and temperatures reaching above zero in the valley by the weekend. It looks like only a few cm of snow on Wed and Thurs, but we may see 20-30 cm and rain in the valley bottom over the weekend.
