Avalanche forecast

Banff Yoho Kootenay

Dec 19 – 20, 2018Parks Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

More snow is raising the avalanche danger. It is a good time to stay out of backcountry avalanche terrain and shred some pow at your local ski hill!

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5
    Another 25-40 cm of new snow is forecast by end of day Thursday. This is falling on 50-70 cm deep storm slabs that have been reactive over the last week. These slabs are sitting on the Dec. 10th layer of facets and surface hoar.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1.5–3
    The mid and lower portions of the snowpack are weak and are now overloaded with critical levels of snow. We expect avalanches to step down to this deeper layer, especially in thinner snowpack areas.

Weather Forecast

Two significant frontal systems are lined up to move inland over the next three days. 25-40 cm of additional new snow is expected along the divide by end of day on Thursday. This snow will be accompanied by moderate to strong SW winds. Freezing levels remain at valley bottom. On Friday, temperatures cool with lighter windspeeds and snow amounts

Snowpack Summary

Another 5-10 cm of snow has fallen on Tuesday bringing the total to 50-70 cms sitting on top of the Dec 10th weak layer (facets and surface hoar). Fresh windslabs can be expected on lee (north and east) aspects. The lower snowpack is weak and facetted. Any avalanches initiated in the storm snow have potential to step down to this lower layer.

Avalanche Summary

Numerous natural and skier (or explosive) triggered avalanches up to 2.5 have been reported over the past few days. Avalanches may run further down slope than expected, so be cautious of overhead hazard.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

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