Avalanche forecast

Sea To Sky

Apr 14 – 15, 2016Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
No rating
Treeline
No rating
Below
No rating
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Highlights

Friday is probably the last reasonable day for a big objective for the foreseeable future, as a significant warm up is expected to begin Saturday. The odd wind slab in the alpine may still be sensitive to human triggering.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Stay alert Friday, a few lingering wind slabs may still be sensitive to human triggering in the alpine.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    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
    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.

Weather Forecast

Temperatures are expected to be on the cooler side again Friday before the big wave of warmth crashes into the region Saturday morning. FRIDAY: Freezing level starting at 1100 m, topping out at 1500 m, light to moderate southwest wind, no significant precipitation expected. SATURDAY: Freezing level beginning around 1500 m, climbing to around 2500 m in the afternoon, no significant precipitation, light variable winds at and below treeline, moderate southwest wind at ridgetop. SUNDAY: Freezing level beginning near 2800 m, rising to around 3500 m by the afternoon, no significant precipitation, moderate southwest wind.

Avalanche Summary

On Wednesday small storm and wind slabs to size 1.5 were reported running on a variety of aspects. On Tuesday, explosive control work near Whistler produced several size 2 cornice triggered avalanches.

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. Deeply buried weak layers in the mid snowpack and near the ground still have the potential to wake up and become active with a rapid warm up. While unlikely, releases on these deeply buried weak layers would result in very large avalanches. 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.

Regions covered