Take a cautious approach to wind-loaded areas as recently formed wind slabs may remain reactive to human triggering.
Concern for buried weak layers warrants conservative terrain choices and avoidance of steep and convex slopes.
Strong wind has shifted from northeast to southwest on Friday and is expected to continue throughout the day on Saturday. Shifting winds will leave fresh wind slabs on a wide variety of aspects in the alpine and along ridges.
A layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. This layer produced natural avalanches last week, and recent snowpack observations suggest it could still be reactive to human triggering on steep rocky slopes.
On Friday, a small (size 1.5) natural wind slab was observed on a northwest aspect in the alpine in the north of the region.
On Thursday, as northeasterly winds increased, a natural size 2 wind slab was observed. This avalanche occurred as a result of rapid snow loading from wind transport. The avalanche failed on a weak layer of surface hoar, which contributed to the wide propagation of the avalanche. See full report here.
Over the last week, there were several reports of larger (up to size 2.5) natural avalanches at all elevations releasing on a 30 to 60 cm deep facet layer. Triggering an avalanche on this weak layer is still possible under the current conditions.
Recent strong to extreme winds have formed drifts, wind-scoured areas, and wind slabs in alpine terrain and along ridges. Sheltered terrain has 10 to 15 cm of low-density snow. This snow may sit above a layer of small surface hoar that will sluff easily in steep terrain. A weak layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. Recent avalanche activity and snowpack tests suggest human triggering is possible for this layer. We are uncertain about the layer's spatial distribution, but observations suggest it is fairly widespread.
Saturday night
Clear periods. Alpine temperatures drop to a low of -4 °C. Ridge wind southeast 10-30 km/h. Freezing level at valley bottom.
Sunday
Cloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -4 °C. Ridge wind southeast 15-25 km/h. Freezing level rises to 400 metres.
MondayCloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -6 °C. Ridge wind southeast 15-25 km/h. Freezing level rises to 400 metres.
TuesdayMainly cloudy with isolated flurries. Alpine temperatures reach a high of -6 °C. Ridge wind southeast 20 km/h. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
