Avalanche forecast

Northwest Coastal

Feb 4, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

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

Reactive storm slabs are building at higher elevations. Take a cautious approach to terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    A weak layer exists 60-100 cm below the surface. It may still be possible for humans to trigger persistent slab avalanches on this layer, and storm slab avalanches could step down to this layer.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2
    Storm slabs exist and will continue to grow with the incoming snow and wind. They will be most reactive at higher elevations and in wind-affected terrain.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Sunday

Weather Forecast

SUNDAY: An approaching warm front brings 20 cm to southern and coastal parts of the region and 5-15 cm elsewhere with moderate southwest wind and alpine high temperatures around -8 C.MONDAY: A break in the storm with some isolated flurries, light to moderate west wind, alpine high temperatures around -5 C.TUESDAY: Another storm brings 20-40 cm with strong to extreme southwest wind and freezing levels climbing to around 1800 m.

Avalanche Summary

Natural avalanche activity was observed on Friday morning, producing several 30 cm thick slabs in the latest snow. A large (size 3) storm slab avalanche was reported on a east aspect east of Terrace.A few persistent slab avalanches released on Wednesday, most likely failing on the mid-January crust. This included a natural size 3 avalanche on a southwest slope at 1150 m near Exstew and a few skier triggered slabs (size 1-2) in thinner snowpack areas (east of Terrace and the northern part of the region). Overall, activity on persistent weak layers has been limited, but large persistent slab avalanches may remain possible during periods of heavy loading or rapid warming.

Snowpack Summary

The region received up to a metre of snow over the past week, but warm temperatures have promoted settlement and reduced this amount to 50-70 cm. Westerly winds are blowing snow around in exposed areas. A weak layer buried in mid-January is 60-100 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 treeline and below. This layer produced a few human triggered avalanches throughout the region over the past week, and 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 100 cm below the surface, but may be triggerable from thin spots.

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