Avalanche forecast

Banff Yoho Kootenay

Mar 3 – 4, 2023Avalanche Canada
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Avalanche danger

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

Some light snow and moderate winds will likely keep the danger elevated Friday. It is March, but forecasters have little faith in the snowpack given the deeper weak layers.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2

    Reports of wind slabs being reactive in some locations. Remain vigilant in lee areas with new snow and wind where wind slabs are more likely.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Three persistent weak layers formed in January are down 70-100 cm. The biggest concern is triggering these buried suncrusts on steep solar slopes, but weaker facets and isolated surface hoar can be found on the same interface on shaded aspects.

  • Deep Persistent Slabs

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

    Weak facets and depth hoar are present at the bottom of the snowpack which inspires very little confidence. Be especially cautious in thin snowpack areas, which are likely areas for triggering.

Confidence

Moderate

Avalanche Summary

Lake Louise ski hill reported explosive-triggered size 1 stiff wind slabs, and smaller natural avalanches in steep, unsupported terrain. Also, semi-circular bowl (Lake Louise ski hill backcountry) slid naturally. It was reported as a size 2 with no information about what type of layer it slid on.

Snowpack Summary

Wind slabs are present in the alpine and at treeline. These wind slabs overlie the various Jan PWL interfaces of sun crusts, facets, and surface hoar down 80-120 cm. The weaker Nov. 16 basal facet layer is down 100-200 cm and produces moderate to hard sudden collapse results. Deeper snowpack areas west of the divide are stronger and more supportive than areas to the east.

Weather Summary

30-50km/h winds and convective flurries (2-5cm) Thursday night into Friday AM.

Friday: During the day, expect another few cm over Western slopes with ridgetop SW winds at 30-40km/h. Alpine temperatures will be in the -5 to -10C range with freezing levels at valley bottom.

Saturday: A weak upper ridge with weakening SW winds (20-30km/h) will give way to cloudy skies and flurries with light winds shifting to the East.

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Terrain and Travel Advice

  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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