Regions
South Coast Inland.
Wind slabs are still lingering on many slope aspects at upper elevations. Analyze each slope for signs of wind loading and likely trigger points as you travel.
Confidence
High - The weather pattern is stable
Weather Forecast
Thursday: Mainly cloudy with isolated flurries delivering a trace of new snow in the south of the region. Winds light from the southwest. Alpine temperatures around -7.Friday: Cloudy with isolated flurries bringing up to 4cm of new snow to the south of the region and a trace elsewhere. Winds light to moderate from the southwest. Freezing level rising to 600 metres with alpine temperatures to -9 in the north, -4 in the south.Saturday: Mainly cloudy with isolated flurries bringing a trace of new snow to the north of the region. Winds light from the southeast. Freezing level rising to 800 metres in the north of the region and 200 metres in the south. Alpine temperatures around -6.
Avalanche Summary
Reports from yesterday included a MIN report of an avalanche involvement in the Duffey Lake area, notable for the heightened consequences of triggering hard wind slab from below the fracture line. No new natural avalanches have been observed, but evidence of a natural avalanche cycle in the Duffey Lake area was reported on Monday, where several natural Size 1-2.5 avalanches ran over Sunday night. Slab depths ranged from 20-60 cm and although most avalanches had slid on southwest aspects, southeast, east, and northeast aspects were also represented. A MIN report from Monday also details a skier triggered Size 1.5 avalanche on Vantage Peak, notable for its approximately 100 cm crown depth revealing significant loading from recent winds.
Snowpack Summary
Most parts of the region saw 60-90 cm new snow last week, which is reported to be generally bonding well to underlying snow. With that said, the critical issue under our current conditions is determining where wind slabs have been formed in response to recent strong winds redistributing our new snow. Buried below the new snow, a facet/surface hoar layer that was observed in the Duffey Lake area does not seem to have turned into a major concern. For low snow areas such as the Chilcotins, another concern is a layer of faceted snow from mid-December that is buried under approximately 50 cm of snow. This mid-December interface is now down over 1 m in most other areas and is generally considered to be stable, except in shallow snowpack areas as mentioned above, where snowpack tests indicate it could still be a viable failure plane.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.