Avalanche forecast

Northwest Coastal

Mar 11 – 12, 2012Avalanche Canada
View on map
Archived · expired 15 years ago

Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Forecast strong winds and new snow will create fresh and reactive wind slabs in unusual places, but generally lurking below ridgecrests, behind terrain features and in gullies.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–6
    It is still possible to trigger early-February persistent weaknesses where they exist. Any avalanches failing on these layers are expected to be large and destructive.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Monday: Light snowfall - strong easterly winds changing to southwesterly by mid-day - freezing level at 350m Tuesday: Light snowfall - strong southwesterly winds - freezing level at surface Wednesday: Light to moderate snowfall - strong southeast winds - freezing level rising to 600m

Avalanche Summary

A skier released a size 1 hangfire slab (overburden from a previous avalanche) in the northern part of the region. The avalanche occurred on a south aspect at 900m and is thought to have reacted on the early February interface. No other avalanches were reported. Observations were most likely reduced by poor visibility.

Snowpack Summary

Continued strong westerly winds have redistributed recent storm snow into reactive wind slabs that most commonly exist at treeline and in the alpine. In the northern part of the region two persistent weak layers are on the radar of some operators: Surface hoar buried at the beginning of March is as much as 70cm deep. The early February persistent weak layers (surface hoar, facets, crusts) are over a metre down. Although not widespread throughout the region, persistent slabs would be destructive in nature and may be reactive to skier triggers, particularly below treeline on isolated and sheltered steep terrain where buried surface hoar may be preserved. Cornices in the region are reported to be large and unstable.

Regions covered