Avalanche forecast

South Coast

Apr 10 – 11, 2016Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
No rating
Treeline
No rating
Below
No rating
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Highlights

Spring Conditions. Expect avalanche hazard to increase throughout the day, especially during periods of warm, sunny weather. Failing cornices could trigger large avalanches running to valley bottoms. Watch out for what's above your head.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–5
    If the sun is shining, cornices present a significant hazard. Even if they don't trigger a slab avalanche when they fall onto a slope, they have a nasty habit of running surprisingly long distances.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Solar radiation in the spring can rapidly change the hazard from low to high. Plan ahead and monitor the effect of solar radiation carefully.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–6
    Ongoing sunny weather and warm temperatures could lead to destructive wet slabs, especially if there is little or no overnight refreeze.

Weather Forecast

MONDAY: Freezing level: 2000m, mostly cloudy, light southwesterly ridgetop winds. TUESDAY: Freezing level: dropping to 1500m, 10-15mm of precipitation throughout the day and overnight, moderate to strong southerly ridgetop winds. WEDNESDAY: Freezing level: 1500m, light precipitation, light southwesterly ridgetop winds.

Avalanche Summary

No new avalanches were reported on Saturday.

Snowpack Summary

Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. Monitoring the overnight freeze of the snow surface is very important during the spring. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating and solar radiation will weaken the snowpack much more quickly than it would if there is a well frozen thick crust. This is because the crust must first melt before the sun can weaken the snowpack. There is an old crust layer down approximately 50cm in the Duffey area and north of Pemberton. This layer has generally been dormant but resulted in a couple large avalanches during the last major warming event and produced a couple explosive triggered avalanches on Thursday. With continued warming, this layer could wake-up in isolated locations such as steep, rocky faces. Glide cracks are widespread, active, and best avoided. Low elevation and thin snowpack areas have become isothermal, meaning the snowpack is 0 degrees Celsius throughout. An isothermal snowpack is more prone to full depth wet slab avalanches during the heat of the day, especially on steep, rocky faces.

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