Avalanche forecast

Sea To Sky

Dec 30 – 31, 2011Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    3–6
    Deep and dense wind slabs exist below ridge crests, behind terrain features and in cross-loaded gullies. Cornices are large and fragile and can act as triggers for avalanches on the slope below.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–5
    Weaknesses within and at the base of the storm snow may be triggered naturally (by solar radiation or wind-loading) or by the weight of a person. Storm slabs could fail on deep persistent weaknesses.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Sunday

Weather Forecast

Saturday: Dry and cool. Expect sunshine to hit the mountains for the first time in a while. Freezing level 500m. Light north-west winds. Sunday: Moderate precipitation, with the freezing level rising from 1500m to 2000m by Sunday night, when the heaviest precipitation is forecast to fall. 15-20mm. Moderate to strong southerlies.Monday: Light-moderate precipitation, mainly in the morning. Freezing level gradually lowering.

Avalanche Summary

Numerous Size 1-3 slab avalanches (both natural and human triggered) have been reported in the past few days. Skiers accidentally triggered avalanches in Garibaldi Park (Wednesday) and in the backcountry near Blackcomb (Thursday). In both cases they had a lucky escape.

Snowpack Summary

Another 10cm of snow fell last night bringing the total snowfall in the past week to 100-180cm. Weaknesses exist within, and at the base of, the storm snow. New and old wind slabs have formed in exposed NW-E facing slopes, 1m deep in some areas. Cornices have grown large and could act as a trigger for large avalanches. A weak rain crust is found below the new snow up to treeline elevations. This crust may sit on top of buried surface hoar and/or facets. A strong mid pack overlies basal facets that have also gained considerable strength. On average the snowpack is around 200cm deep near treeline. A key concern on Saturday is the forecast sun hitting the new snow for the first time. This could act as a trigger for natural avalanches.

Regions covered