Avalanche forecast

Banff Yoho Kootenay

Dec 22 – 23, 2018Parks Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Nice weather Saturday but there are two significant weak layers in the snowpack and some fresh wind slabs. Natural activity will likely taper, but the snowpack is primed for human triggering. SH

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Fresh wind slabs from strong winds over the last 2 days have formed within the new storm snow. These will be most prevalent in the lee of features and may stay reactive over the next couple of days.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5
    The Dec. 10 persistent layer of facets and surface hoar is now buried 40 - 80cm. Avalanches have either been independently running on this layer, or stepping down to the basal weakness.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3
    Recent snow has now overloaded the Oct. 26 deep persistent layer of facets and depth hoar, and there is enough mass now to cause large avalanches.

Weather Forecast

Mainly sunny skies and cold (-15°c to -20°c) for Saturday. Winds will diminish and be light to moderate from the NW. Some light snow Sunday but overall no major systems in the forecast for the next week.

Snowpack Summary

An average 40-80 of recent storm snow with variable wind effect now sits over the Dec 10th facet/surface hoar interface. In many areas the lower snowpack is weak with the October 26 depth hoar, facets and crust near the base. Snow pack depths range from 90-160 cm at ~2000 m.

Avalanche Summary

Numerous natural avalanches up to size 2.5, as well as several skier remote and skier triggered avalanches up to size 2 have been observed in the last several days. One explosive controlled avalanche today at Sunshine Village went close to 2m deep on the basal weakness. This pattern is likely to continue for the next while.

Confidence

Regions covered