Avalanche forecast

South Columbia

Mar 26 – 27, 2016Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Triggering lingering storm slabs and fresh wind slabs is possible on Sunday, mainly from steep, north-facing alpine terrain. 

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    Cornices are an ongoing concern and should be treated with respect. Failing cornices have potential to trigger stubborn persistent weaknesses.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–6
    The persistent weak layer of buried surface hoar, facets, and crusts is buried down close to a metre. This has become a low probability of triggering, but high consequence of large avalanche problem.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Fresh storm slabs may be sensitive to rider triggering, especially in steep wind-loaded terrain.

Confidence

High

Weather Forecast

SUNDAY: Periods of snow – around 10 cm. The freezing level is around 1400-1500 m. Winds are moderate from the W-SW. MONDAY: A mix of sun and cloud. The freezing level climbs to 1800-2000 m and winds ease to light. TUESDAY: Mainly sunny. The freezing level is around 2000 m and winds are light.

Avalanche Summary

On Friday there was one report of a very large (size 4) persistent slab on a large south-facing slope that was triggered by new snow loading. This avalanche likely failed on the late February interface. There were also numerous reports of natural storm slabs up to size 2.5, a few natural cornice falls, and several skier triggered slabs up to size 1.5. The majority of recent avalanches occurred on northerly aspects, but there were a few on south-facing alpine slopes as well.

Snowpack Summary

New storm slabs have developed above a mix of surfaces, including crusts on solar aspects, moist snow up to treeline, and dry snow or recent wind slabs in the alpine on shaded aspects. Cornices continue to be described as large and fragile. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60 to 110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. New storm loading above the buried persistent weak layer may increase the likelihood of triggering large avalanches. Expect loose wet avalanches and natural cornice falls during periods of strong solar radiation and/or daytime warming.

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