Stormy conditions will increase the likelihood of triggering large, destructive avalanches over the coming days.
New snow and strong westerly wind will likely form new wind slabs in lee terrain features. Storm slabs may also build in wind-sheltered terrain. The new snow may overly lingering wind slabs that formed on the weekend from northeast wind.
Numerous problematic weak layers exist in the top meter of the snowpack, at prime depths for human triggering. Be especially cautious around steep openings within and near treeline elevations.
A layer of large and weak facets sits near the base of the snowpack. This layer continues to produce very large avalanches that can travel far. The likelihood of natural and human-triggered avalanches will increase as snow accumulates. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain, or by triggering a smaller avalanche that could step down to this layer.
On Sunday, many small to large (size 1 to 3) wind slab avalanches were triggered naturally and by riders, occurring on all aspects at treeline and alpine elevations. Various deep persistent slab avalanches were also triggered naturally, being large to very large (size 2 to 4). The avalanches occurred on all aspects between 2400 and 2800 m.
High-consequence avalanche activity is occurring daily, which is ongoing for several weeks now. Most of the avalanches over the past week released between 1800 and 2800 m, on all aspects. See here for information on a fatal skier-triggered avalanche incident from last week.
Your best defense is to stay diligent in choosing low-consequence terrain away from overhead exposure. Stay disciplined and adjust your expectation this winter. See more on the potential of triggering deeper weak layers Forecasters' Blog.
New snow and westerly wind will form new wind slabs in lee terrain features. The new snow will overly previously wind affected snow in the alpine and a small layer of surface hoar crystals in wind-sheltered terrain.
A thick melt-freeze crust up to 1700 m around Revelstoke and 2000 m further south is buried about 20 to 50 cm deep. At this same depth, a small layer of surface hoar crystals may be found around treeline and lower alpine elevations in wind-sheltered terrain.
Two layers of surface hoar which formed in early January are 50 to 100 cm deep. These weak layers continue to be reactive to human triggering, although snowpack tests are starting to indicate they may be slowly strengthening.
Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region, as described in the Avalanche Summary.
Monday Night
Cloudy with snowfall, accumulation 5 to 15 cm with local enhancements possible, 20 to 30 km/h west wind, treeline temperature -14 °C.
Tuesday
Cloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible, 20 to 30 km/h west wind, treeline temperature -12 °C.
WednesdayCloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible, 20 to 40 km/h southwest wind, treeline temperature -10 °C.
ThursdayCloudy with snowfall, accumulation 5 to 15 cm, 30 to 40 km/h southwest wind, treeline temperature -5 °C.
More details can be found in the Mountain Weather Forecast.
