Avalanche forecast

Kootenay Boundary

Feb 5, 2017Avalanche Canada
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Archived · expired 10 years ago

Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable

Highlights

Fresh storm slabs will become increasingly sensitive to human triggers as the snow load increases.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Touchy storm slabs becoming more likely to trigger.
  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3
    Smaller storm slabs may step-down to deeper weak layers, resulting in large, destructive avalanches.

Confidence

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

Weather Forecast

Saturday night: 15-20 cm new snow/ Moderate to strong, southwest winds/ Freezing level 800 m.Sunday: 0-5 cm new snow/ Light, southwest winds/ Freezing level 800 m.Sunday night: 15-20 cm new snow / Light to moderate southwest winds / Freezing levels dropping to valley bottoms.Monday: 20-25 cm new snow/ Light, southwest winds/ Freezing level valley bottom.Tuesday: 0-5 cm new snow/ Light, southwest winds/ Freezing level valley bottom.

Avalanche Summary

No new avalanche observations were reported on Friday. Fresh storm slabs will likely have a poor bond to the old snow surfaces and be reactive through the weekend, potentially stepping down and initiating deep persistent slabs.

Snowpack Summary

20-25 cm of new snow has buried a variety of old snow surfaces including stiff wind slab or wind effected snow at upper elevations, sun crust on steep southerly slopes and surface hoar in sheltered areas. Another 15-20 cm is expected by Sunday morning bringing storm totals to 35-45 cm. Below the surface, 50-65 cm of settled snow now sits above an interface that was buried in mid-January. The interface is composed of weak facets, surface hoar, and/or sun crusts and the strength of the bond is reportedly variable. Recent snowpack tests have shown sudden results on that interface. Areas with a shallower snowpack (less than 150 cm) have a generally weak snowpack structure with sugary facets near the ground. This includes shallow alpine slopes and most of the Rossland range. Smaller storm slab avalanches may step-down to these deeper weak layers, resulting in large, destructive avalanches.

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