Avalanche forecast

Northwest Coastal

Feb 13, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

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

Heavy snowfall and strong winds are forecast for Tuesday. 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 - Certain
    Size
    1–3
    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

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

A storm arrives early on Tuesday with heavy snowfall and strong winds. TUESDAY: Snow (20-30cm). Ridge wind strong, southwest. Temperature near -2. Freezing level 500 m.WEDNESDAY: Cloudy with sunny breaks. Ridge wind moderate to strong from the north / west. Temperature -5. Freezing level valley bottom.THURSDAY: Snow in the afternoon. Ridge wind strong from the west. Temperature -6. Freezing level valley bottom.

Avalanche Summary

On Saturday, natural wind slab avalanches to size 2 were reported on east aspects (due to north westerly winds) at higher elevations near Terrace.

Snowpack Summary

Strong and variable winds occurred throughout the long weekend, redistributing last week's storm snow and creating fresh wind slabs at higher elevations. 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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