Highly unpredictable and largely unsurvivable deep persistent slab avalanches will likely remain a concern for the foreseeable future. Continued conservative terrain selection is crucial for safe travel.
Summary
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Friday: Cloudy with sunny periods and isolated light snow flurries in the morning becoming mainly cloudy with light snow in the afternoon. Freezing level reaching 1500 m with light to moderate southwesterly alpine wind. Friday night and Saturday: Mainly Cloudy with light snow bringing 10-20 cm of total accumulation. Freezing level around 1600 m and Moderate SW alpine wind. Sunday: Unsettled conditions with light snow flurries. Freezing level as low as 700 m in the north and as high as 1500 m in the south, and light southwesterly alpine wind.
Avalanche Summary
Reports from Wednesday include widespread human triggered and isolated natural storm slab, wind slab and loose dry avalanches. All the avalanches reported failed within the recent storm snow, were very touchy and propagated easily; however, most were small, low density and predictable. Recent very large deep persistent slab avalanches in neighboring regions highlight a low probability, but high consequence avalanche problem that also plagues the South Columbia region. These highly destructive and largely unpredictable avalanches are expected to be isolated, but certainly possible anywhere at anytime.
Snowpack Summary
Weaknesses exist within and under the 40-70 cm of rapidly settling recent storm snow, including small surface hoar, thin sun crusts, rain crusts, and/or small facets. These weaknesses are currently reactive to light triggers, especially on wind-loaded slopes. Some big cornices have also become weak.There are three persistent weak layers that contribute to a highly variable, fundamentally unstable, complex snowpack with step-down potential. The mid-March sun crust/surface hoar layer down 50-80cm still has potential for human-triggering in isolated areas. The early-March crust/facet/surface hoar layer down around 80-120cm has become less susceptible to human-triggers, but still has the potential to produce large avalanches, and we continue to see fractures stepping down to this layer. The mid-February crust/facet/surface hoar layer is typically down at least 1.5m and direct triggering has become unlikely. However, large loads like cornices or smaller avalanches stepping down can still trigger this layer and produce very large avalanches.
ccampbell,
Avalanche Canada
