Avalanche forecast

South Columbia

Mar 16 – 17, 2013Avalanche Canada
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Avalanche danger

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

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–6
    Recent stormy weather has formed large and potentially weak cornices. Cornice falls may be highly destructive, and could also trigger large avalanches on the slope below.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–6
    New snow accumulations are forecast to add load to an existing storm slab problem which has produced destructive avalanches in recent days. Expect increased reactivity in wind-affected terrain or in areas where buried surface hoar exists.

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

Saturday night and Sunday: Moderate snowfall becoming light on Sunday / Moderate southwest winds becoming light and northwesterly with strong gusts / Freezing level at 800mMonday: Light snowfall / Light west winds with strong gusts / Freezing level at 700mTuesday: A mix of sun and cloud with snowfall developing late in the day / Light southwest winds / Freezing level at 1200m

Avalanche Summary

A widespread natural slab avalanche cycle to size 3.5 was reported on Thursday and Friday.  Avalanche activity occurred on all aspects and elevations. At lower elevations where rain fell, wet slabs and full-depth glide crack releases were observed. At higher elevations, activity occurred within the recent storm snow, or at the March 10th surface hoar interface.

Snowpack Summary

At treeline and above, light amounts of new snow overlie deep and cohesive storm slabs that formed with heavy snowfall, strong southwest winds and warm temperatures. Widespread cornice development has also taken place. At lower elevations rain penetrated the snowpack, and below 1400m the snowpack was reported to be isothermal. The recent storm snow overlies a weak layer of surface hoar or a sun crust that were buried on March 10th. Some areas had strong winds before the surface hoar was buried, so its distribution may be specific to sheltered and shaded terrain features. Some professionals are still expressing concern for the layer of surface hoar buried on February 12th. This interface is now well over 1.5m below the surface and triggering has become unlikely.

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