Avalanche forecast

Sea To Sky

Dec 1 – 2, 2012Avalanche Canada
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Avalanche danger

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

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–5
    New storm slabs and wind slabs are building at higher elevations. Natural and rider triggered avalanches are likely; especially on lee slopes, and behind terrain features that have been wind loaded.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–6
    Slopes with smooth ground cover and reloaded bed surfaces may be prone to remote triggering and step down avalanches. Typical trigger points include thin rocky areas. May be difficult to trigger, but often very large with serious consequences.

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain on Tuesday

Weather Forecast

The recent weather pattern continues, with a very persistent deep low off the coast driving a moist, mild SW flow over the region. Moderate accumulations are expected through the forecast period, accompanied by moderate S-SW winds. Sunday: Fzlvl’s 1200 m, snow amounts 5-10 cm, ridgetop winds SE 15-25 km/hr, alpine temps -4.Monday: Fzlvl’s 1200 m, snow amounts 8-15 cm, ridgetop winds S 35 km/hr, alpine temps -4.Tuesday: Fzlvl’s 1700 m in the am then falling to 900 m in the afternoon, snow amounts 10-15 cm, ridgetop winds S 30 km/hr, alpine temps -3 falling to -8.

Avalanche Summary

Explosive testing produced numerous size 1-1.5 slab avalanches on NW-N aspects. All instabilities reacting within the storm snow.

Snowpack Summary

Storm slabs and fresh wind slabs have loaded a variety of weak surfaces. These (now buried) surfaces consist of large surface hoar, a thin sun crust, and surface facets. Below this, the mid-pack seems to be fairly settled, strong and bridging instabilities that may exist deeper.Under the mid-pack (90-150 cm down) sits the early November facet/ crust persistent weakness. Recent snowpack tests have shown sudden collapse (or "drops") results on the early November facet/crust deep persistent weakness, but because this weakness is so close to the ground in most areas, any associated avalanche activity will likely be limited to slopes with smooth ground cover (e.g. scree slopes, rock slabs, summer firn, glaciers, etc.). Areas that are most susceptible to trigger this deep persistent weakness are shallow, thin and variable snowpack deposition spots.To view a recent snow pit profile from the Spearhead Range, check out the Wayne Flann Avalanche Blog.

Regions covered