Avalanche forecast

Northwest Coastal

Apr 4 – 5, 2012Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Generally lurking below ridgecrests, behind terrain features, and in gullies. Thick fresh wind slabs are likely sensitive to human triggers and cornice falls, especially with warming and sun-exposure.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Large and weak cornices could easily start popping off with sun-exposure. Not only are they a hazard in themselves, but can also act as a heavy trigger for very large avalanches on the slope below.

Confidence

Good

Weather Forecast

A ridge of high pressure is expected to keep the northwest ranges mainly sunny and dry with light winds throughout the forecast period. Freezing levels are expected to reach 1000m on Thursday afternoon, but Friday and Saturday should be colder with 500m freezing levels.

Avalanche Summary

Reports from Tuesday include evidence of a widespread natural cycle to Size 3 primarily due to wind-loading during Monday's storm. On Tuesday afternoon, sun-exposure caused numerous wet loose avalanches up to Size 2.0 involving the recent storm snow running on a sun crust. Large glide avalanche activity also continued on solar aspects.

Snowpack Summary

15-40cm of new snow is generally bonding well to the previous predominately crusty snow surface. However, sheltered shady slopes may be harbouring buried surface hoar and/or preserved old storm snow from last week, which isn't as stable. Furthermore, not only will daytime warming and sun-exposure cause surface snow to lose cohesion, they will also increase settlement rates and decrease slab stability.

Regions covered