Avalanche forecast

Sea To Sky

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
    3–6
    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 - Likely
    Size
    1–4
    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
    4–6
    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: dropping to 1500m, mostly cloudy, light to moderate southwesterly ridgetop winds. TUESDAY: Freezing level: 1500m, overcast skies,  light to moderate southerly ridgetop winds. TUESDAY NIGHT: 15-20mm of precipitation with freezing levels dropping to near 1000m and moderate southerly ridgetop winds. WEDNESDAY: Freezing level: 1000m, light precipitation, light southerly ridgetop winds.

Avalanche Summary

On Saturday, a size 2 wet slab avalanche was reported as being possibly remotely triggered by a helicopter on a southeast aspect at 1900m. Additionally, numerous wet loose avalanches to size 2 were observed on solar aspects at treeline and in the alpine.

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