Avalanche forecast

Northwest Coastal

Feb 14, 2018Avalanche Canada
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Avalanche danger

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

Avalanches will remain very likely in the wake of Tuesday's massive storm. Avoid all avalanche terrain, free from overhead hazard.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–4
    A weak layer exists 120-150 cm below the surface. It may still be possible for humans to trigger persistent slab avalanches on this layer, or for a storm slab release to step down to this layer resulting in a very large avalanche.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–3.5
    Heavy snowfall and strong to extreme winds are a recipe for rapid loading and widespread avalanches.... it's a good time to avoid all avalanche terrain!

Confidence

High -

Weather Forecast

We'll have unsettled conditions in the wake of Tuesday's awesome storm. WEDNESDAY: Cloudy. Ridge wind moderate to strong from the north / west. Temperature -5. Freezing level 400m.THURSDAY: Snow in the afternoon (5cm). Ridge wind strong from the west. Temperature -6. Freezing level valley bottom.FRIDAY: Cloudy. Ridge wind moderate to strong from the north / west. Temperature -5. Freezing level 400m.

Avalanche Summary

We haven't received reports (yet) but we anticipate a widespread natural avalanche cycle occurred on Tuesday.

Snowpack Summary

Phenomenal snowfall amounts occurred on Tuesday, with 40-50cm falling in a 12 hour period near Terrace! Combine that with strong north west winds and temperatures near zero... it's a perfect recipe for widespread large destructive avalanches. All this new snow sits on a wide array of surfaces - either wind scoured from strong and variable winds from the long weekend, or fresh wind slabs at higher elevations on lee (downwind) slopes. Beneath the storm snow lies a 5-20 cm thick crust that was buried early February and can be found 60-110 cm below the surface on all aspects up to 1400 m. A weak layer buried in mid-January is 120-150 cm below the surface and remains a concern. In most areas this layer is a crust, but it may also be surface hoar in sheltered areas at tree line and below. This layer may remain reactive as it adjusts to the weight of the new snow.In thinner snowpack areas (north and inland), deeper crust / surface hoar layers that were buried in December and early January may still be a concern. They are buried over 150 cm below the surface, but could still be reactive and triggered from shallow spots.

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