Avalanche forecast

Kootenay Boundary

Dec 23 – 25, 2019Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanche observations in the wake of the storm are extensive and artificial triggers continue to cause very large and destructive avalanches. These avalanches are releasing on a variety of weak snowpack layers. Conservative terrain selection remains absolutely essential.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–3.5

    Three different weak layers may be found in the snowpack. It is uncertain whether the rapid loading from the storm cleaned them out and hence whether they will remain a concern in the distant future. Until more evidence exists, it is prudent to assume the layers are present and capable of forming very large, destructive avalanches. Best to avoid alpine terrain until the uncertainty about these layers decreases.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    Snowfall totals will reach around 60 to 90 cm across the region from the weekend's storm. The snow (and rain at lower elevations) fell with strong west wind, forming touchy slabs that have produced large and destructive avalanches. Storm slabs are expected to remain reactive to skier traffic on Monday.

Confidence

High -

Weather Forecast

Monday night: Cloudy with isolated flurries and a trace of new snow. Light southwest winds.

Tuesday: Cloudy with continuing isolated flurries and a trace of new snow. Light southwest winds. Alpine high temperatures around -7.

Wednesday: A mix of sun and cloud with cloud decreasing. Light northeast winds. Alpine high temperatures around -8.

Thursday: Mainly sunny with cloud increasing over the day. Light to moderate southwest winds. Alpine high temperatures around -7.

Avalanche Summary

A widespread avalanche cycle occurred on Saturday, with observations of large artificially triggered avalanches continuing into Sunday. Many of these recent avalanches released within the storm snow, and large avalanches have been observed on all aspects and generally above 2000 m. Numerous other large to very large avalanches have also been triggered by explosives on the late-November layer described in our Snowpack Summary.

Snowpack Summary

The past few stormy days have seen around 60 to 90 cm of snow deposited in the region, accompanied by strong west wind. This snow has loaded multiple weak layers, including:

  • a feathery surface hoar layer now buried around 60 to 100 cm.
  • an older surface hoar layer buried about 80 to 120 cm, associated with a melt-freeze crust on steep south aspects.
  • a complex layer of weak and sugary faceted snow, surface hoar, and melt-freeze crusts in the bottom half of the snowpack, buried in late November.

There is uncertainty on which of these layers will emerge as our primary persistent slab problem. However, given our extensive recent avalanche activity, it is prudent to expect that any one of these deeply buried layers could produce large and destructive avalanches with a human trigger. 

Terrain and Travel

  • Don't let the desire for deep powder pull you into high consequence terrain.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Make conservative terrain choices and avoid overhead hazard.

Regions covered