Avalanche forecast

South Coast

Mar 19 – 20, 2015Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

New snow, strong winds and rising temperatures make a great recipe for avalanches. Add in a touchy weak layer buried in the upper snowpack and things may get a bit spicy.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Reports of remote triggering from distances of up to 100 m indicate that persistent slab avalanches should be high on our radar. The buried crust/facet layer could produce surprisingly large avalanches now that it is getting overloaded with snow.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Snow and winds are expected to form slabs that could fail naturally, or be triggered by the weight of a person or sled.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Moderate to heavy precipitation is expected to continue until late Saturday. Anticipated amounts: by Friday morning – 15-20 cm; Friday – 5-15 cm; Saturday – 5-10 cm. The freezing level is the big question. It looks like it will hover around 1700 m, dropping towards 1200 m on Saturday. Winds are moderate to strong from the S-SW.

Avalanche Summary

On Wednesday, a size 2 slab avalanche was remotely triggered from a distance of 100 m. The avalanche failed on a north aspect at 2050 m between the Duffey Lake road and Gates Lake. This avalanche failed on the recently buried crust/facet combo, and speaks to the potentially touchy nature of the interface. Skiers also remotely triggered a size 2, which sympathetically triggered a size 1 slab, on the same persistent weak layer on a north aspect. New snow and wind may overload this weakness, creating destructive avalanches. A cycle of wind slabs and storm slabs (mostly size 1, up to size 2) was reported on Sunday and Monday. These failed naturally and were triggered remotely by skiers as well. Many were on north aspects. A snowmobiler also triggered an avalanche on Sunday in the Hurley area (check out the blue pin on our forecast map).

Snowpack Summary

New snow will be landing on old hard wind slabs and wind-scoured surfaces. New storm slabs are expected to develop. Cornices may also be fragile. A crust/facet combo down 10-60 cm is causing trouble (see avalanche summary) and produces moderate, sudden results in snowpack tests. Avalanche problems associated with this layer may linger for a while, with the potential for large and destructive avalanches. A second, deeper crust marks the boundary with a lower snowpack that is reported to be generally well-settled and strong. Below treeline, the diminishing snowpack is trending isothermal (same temperature throughout).

Regions covered