New wind slabs, buried wind slabs, and lingering persistent slabs are maintaining a complex mix of avalanche problems. Be mindful of how this mix changes by elevation. Expect to find touchier surface instabilities in areas with new snow.
Summary
Confidence
High -
Weather Forecast
Saturday night: Clear with cloudy periods. Light northeast winds.Sunday: Sunny. Light northeast winds. Alpine high temperatures around -15.Monday: Sunny. Light northeast winds. Alpine high temperatures around -11.Tuesday: Sunny with cloud increasing in the evening. Light east winds. Alpine high temperatures around -8.
Avalanche Summary
Observations from Friday showed a few small (size 1) wind slabs releasing with skier traffic on east aspects at ridgetop. Small (size 1-1.5) loose dry avalanches were also observed releasing naturally from steeper, sun exposed slopes. On Wednesday, a few rider triggered wind slab avalanches up to size 2, on primarily north aspects at treeline and above were reported.Persistent slab avalanche activity on the mid-January weak layer has slowed down, but not stopped. This layer has created a low likelihood, high consequence scenario in the snowpack at treeline and below. Check out the great photos from a recent
MIN. Take note of the low angle terrain and the light load of a single ski track that triggered this avalanche. This avalanche also stands out for its 2000 m elevation, which is considerably higher than most recent persistent slabs have been reported.
Snowpack Summary
Spotty convective flurries brought up to 30 cm of low density new snow to a few areas of the region at the end of the week. This new snow likely overlies sun crust on sun-exposed aspects. Below any new snow, recent strong northeasterly ridge-top winds have created wind slabs on lee features at treeline and above. Under this wind affected layer, older buried wind slabs exist on a variety of aspects. These remain a concern for overlying facets (weak, sugary snow), causing them to remain reactive for longer than is typical for a wind slab problem.There are two prominent weak layers in the upper snowpack. One was buried at the end of January, and the other mid-January. They are approximately 40- 60 cm and 60-90 cm below the surface. Both layers consist of surface hoar (weak, feathery crystals) and may be associated with a crust on steep, south facing slopes. These weak layers have been most prominent and most reactive below treeline.The lower snowpack is generally considered to be strong, except for shallow, rocky areas where the cold temperatures continue to facet (weaken) the snowpack.
cgarritty,
Avalanche Canada
