Avalanche forecast

South Columbia

Mar 12 – 13, 2016Avalanche Canada
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Avalanche danger

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

  Although persistent weak layers have become less likely to trigger, the consequences of an avalanche could be high. Conservative terrain selection is highly recommended.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Watch for new wind slab development on Saturday night. Forecast snowfall amounts are uncertain, so pay close attention to how much snow falls in your area, and choose terrain accordingly.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    Large cornices loom over open bowls and alpine faces. Not only are massive cornice falls a hazard in themselves, but they can also act as a heavy trigger for slab avalanches on the slope below.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    A persistent weakness lies buried up to 90cm below the surface. Although this layer is slowly becoming less likely to trigger, it has the potential to surprise with nasty consequences. I'd continue riding with a conservative mind set.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Saturday

Weather Forecast

Saturday night: 5-8cm of new snow / Strong southwest ridgetop winds / Freezing level at about 1500mSunday: Light flurries with possible sunny breaks / Light to moderate ridgetop winds / Freezing level at about 1400mMonday: 8-12cm of snow / Moderate easterly ridgetop winds / Freezing level at about 1300mTuesday: Mix of sun and cloud / Light ridgetop winds / Freezing level at about 1200m

Avalanche Summary

On Thursday there was a widespread round of natural storm slab activity (mostly in the size 2 range with some results to size 2.5) in response to new snow and strong winds. In one case a size 3 persistent slab avalanche was remotely triggered on an east-facing slope at 2230m. This points to the ongoing touchy persistent slab problem in some areas. On Friday, a size 2 wind slab avalanche was ski cut on a west aspect at 1900m. Solar-triggered cornice falls (to size 2.5) and loose wet avalanches (to size 2)  were also noted. Some of the cornice collapses triggered wind slabs on the slope below. More wind slab activity is expected with wind and snow forecast for Saturday night.

Snowpack Summary

At treeline and in the alpine, light snow accumulations overlie wind slabs which formed during Thursday`s storm. 60-100cm below the surface you'll find a persistent weak layer comprised of surface hoar, facets and/or a thick crust. This layers seems variably reactive. In other words, it's still really touchy in some places while in other places it's really tough to trigger, and there's not much of a reliable pattern telling us what exact aspects are most suspect. I'd continue to be suspicious of steep, unsupported features at treeline and in the alpine as this layer has the potential for very large avalanches. Below this interface, the snowpack is generally gaining strength. At ridgetop, cornices are huge and potentially unstable.

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