Avalanche forecast

Sea To Sky

Mar 6 – 7, 2012Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Intense solar radiation may cause a spike in avalanche activity on sun-exposed slopes.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Generally lurking below ridgecrests, behind terrain breaks, and in gullies. Wind slabs are sensitive to human triggers, and have the potential to step-down to deeper weaknesses and/or propagate into low-angled terrain.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–6
    Touchy weaknesses within and under the recent storm snow are expected to become more reactive with sun-exposure. Cohesionless low-density snow overlying a crust can produce very large loose-snow avalanches.

Confidence

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

Weather Forecast

Wednesday: Mostly clear with light winds and freezing levels rising to around 1200m. Thursday: Increasing high clouds throughout the day with light winds and freezing levels as high as 2500m for the southernmost part of the region. Friday: Mostly cloudy with snow increasing in the afternoon. Freezing levels around 1000m and moderate southwesterly winds.

Avalanche Summary

Reports from Monday include numerous Size 1-2 explosive-triggered and slope-cut soft wind slab avalanches. One of the larger slope-cuts stepped down 60cm to an old buried wind slab, while another failed on a crust buried last week and propagated onto 15 degree terrain. A brief period of strong solar radiation in the morning caused a couple of Size 3 loose snow avalanches on the Squamish-Cheakamus divide. These started off as surface sluffs and eventually entrained all of the recent storm snow on the entire slope and ran full path.

Snowpack Summary

Around 50-60cm of recent low density storm snow and/or weak wind slabs are bonding poorly to a variety of old snow surfaces, including crusts and wind slabs, from last week. Recent winds and precipitation patterns have created a highly variable slab depth with ability to propagate in low angled terrain and a structure conducive to step-down avalanches. The top 10cm or so is becoming moist during the day with sun exposure, and there is still a lot of snow available for reverse-loading if outflow winds pick up.

Regions covered