Avalanche forecast

Purcells

Apr 21 – 22, 2016Avalanche Canada
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Avalanche danger

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

Spring Conditions. No overnight refreeze of the snow surface means it will not take much sun to rapidly increase the hazard.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–4
    Be sure there is more than air under your feet when traveling on corniced ridges.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    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
    3–6
    No overnight surface refreeze will increase the potential for sporadic deep wet slab release.

Weather Forecast

FRIDAY: Freezing Level: 3200m, mostly cloudy with possible flurries, light to moderate southwesterly ridgetop winds. SATURDAY: Freezing Level: 2500m, cloudy with possible flurries, light northwesterly ridgetop winds. SUNDAY: Freezing Level: 2300m, cloudy with possible flurries, light westerly ridgetop winds.

Avalanche Summary

Most commercial operations have closed for the season, and data is becoming sparse.

Snowpack Summary

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. Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. The snowpack in many areas has 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.

Regions covered