Avalanche forecast

Northwest Coastal

Apr 6 – 7, 2012Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    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.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    Steep sun-exposed slopes in the afternoon. Although generally slow moving and in steeper exposed terrain, wet loose avalanches can entrain significant mass and have dire consequences if terrain traps are in the runout.

Confidence

Fair - Due to limited field observations

Weather Forecast

Synopsis: A ridge of high pressure should maintain mainly sunny skies on Saturday and Sunday. Freezing levels should climb to 1400m on Saturday and 1600m on Sunday, and drop to valley bottom overnight. Upper level winds are light and variable. A weak system could spread more cloud and light precipitation on by Monday afternoon into Tuesday. The freezing level should hover around 1500m.

Avalanche Summary

Recent reports include wet loose avalanche activity up to Size 2.0 in response to direct sun exposure. Cornices have also been failing over the past couple of days, some of which triggered wind slab avalanches up to Size 2 on the slope below. Large glide avalanche activity also continued on solar aspects.

Snowpack Summary

The snow surface consists of a sun crust on solar aspects and lower elevations (becoming moist during the day), surface hoar on shady slopes up into the alpine, and dry settling or faceting snow on higher north aspects. Pockets of wind slab are likely in exposed leeward alpine terrain. Sheltered shady slopes may be harboring buried surface hoar and/or preserved old storm snow from last week, which isn't as stable. Not only will daytime warming and sun-exposure cause surface snow to lose cohesion and cornices to weaken, they will also increase settlement rates and decrease slab stability.

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