Avalanche forecast

Northwest Coastal

Mar 15 – 16, 2014Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–5
    The early-March weak layer remains very active and there has been a lot of recent activity on this layer.  Expect much of the new storm activity to release on this layer.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–3
    Heavy snowfall and strong winds continue to build new storm slabs. Expect stiffer wind slabs in leeward features from strong S-SW wind.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–7
    The deep February persistent weak layer has been quiet recently but may reactivate with the weight of the new storm snow. Smaller avalanches have the potential to step down to this deep layer resulting in very large, destructive avalanches.

Confidence

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

Weather Forecast

The storm is expected to end on Sunday night. A break between storms is expected for most of Monday before the next system arrives Monday evening. The north of the region can expect less snowfall amounts than the south.Sat. Night/Sunday: Snowfall 20-40cm, freezing level am: 800m pm: 500m, ridgetop winds 30-50 km/h S-SW easing during the day.Monday: Cloudy with sunny breaks, mostly dry during the day, freezing level am: 300m pm: 600m, ridgetop winds 20-40 km/h W-NWMon. Night/Tuesday: Snow 15-25cm, freezing level am: 500m pm: 1000m, ridgetop winds 30-50 km/h SW

Avalanche Summary

Observations during the storm are limited but we have received reports of wind slab activity and explosive triggered slabs releasing on the early-March layer.  Widespread natural activity is expected for Saturday night and Sunday.

Snowpack Summary

Storm slabs continue to build. S-SW winds are building wind slabs in leeward features. A widespread crust is expected below the storm snow at lower elevations.Before the weekend storm, the early March persistent weak layer was down up to 1m in the north of the region. The south of the region had less snowfall and the slab was down roughly 60cm. This weak layer consists of any of the following: hard wind slabs or wind-scoured slopes in exposed terrain, a thick layer of faceted snow on sheltered/shady slopes, isolated surface hoar on sheltered/shady slopes, and sun crust on steep solar aspects. The early-February weak layer of surface hoar or a crust/facet combo is typically buried over 1.5m deep. This layer continues to react in snowpack tests, primarily on sheltered north aspects around treeline. The weight of the new snow and rain has the potential to reactivate this layer resulting in large, destructive avalanches. Basal facets and/or depth hoar remain an isolated concern in shallow snowpack areas in the northern part of the region.

Regions covered