Avalanche forecast

Northwest Coastal

Feb 2, 2017Avalanche Canada
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Archived · expired 10 years ago

Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Be aware of the potential for smaller avalanches to step down to deeper persistent weaknesses. The avalanche danger may be higher in the north of the region where very large, full depth avalanches remain a concern

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Recent snow on the weekend and wind has accumulated wind slabs in the alpine and tree line lees. Surface avalanches may also step down to deeper, more destructive layers.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–4
    In the mountains closer to Terrace, I'd remain cautious in sheltered treeline terrain where buried surface hoar may be preserved. In the north of the region, full depth avalanches continue to fail on weak layers at the base of the snowpack.

Confidence

Moderate -

Weather Forecast

Thursday: Mix of sun and cloud / Light northeast wind / Alpine temperature -11Friday: Cloudy with sunny breaks and isolated flurries / Light to  moderate east wind / Alpine temperature -13Saturday: Mix of sun and cloud / Light to moderate southeast wind / Alpine temperatures of about -18More details can be found on the Mountain Weather Forecast.

Avalanche Summary

Over the weekend, alpine and treeline features were observed running naturally to size 3.5 in the mountains northwest of Terrace. A few of these avalanches were thought to have failed on buried surface hoar. Several avalanches involving the full depth of snowpack to size 3.5 were also reported in the Ningunsaw and Bell 2 areas. One was reported being remotely triggered by a skier from a distance of 150m away. Moving forward, natural avalanche activity is expected to taper-off with forecast benign weather; however, large human-triggered persistent and deep persistent avalanches remain a concern.

Snowpack Summary

Last weekend, between 60-110 cm of new snow fell with the greatest amounts accumulating in coastal areas. Strong to extreme southwesterly winds accompanied the storm and much deeper deposits can be found in higher elevation lee terrain. At lower elevations, precipitation fell as rain and a surface (or near-surface) crust may now be found below about 1000m. Below the recent storm snow you'll likely find a couple of buried surface hoar layers from January 18th and January 23rd. These surface hoar layers continue to produce easy to hard sudden planar shears in snowpack tests, and should be approached with caution, especially in sheltered tree line terrain. The snowpack below this is generally strong and well settled. The exceptions are areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern.

Regions covered