Avalanche forecast

Kootenay Boundary

Nov 22 – 23, 2011Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

The new snowfall is very exciting, please remember to play safe and avoid avalanche terrain through times of dangerous avalanche conditions.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Strong southwesterly winds will create new wind slabs on lee slopes and terrain features. These wind slabs may be found lower on the slope in unsuspected areas.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–4
    Heavy amounts of snowfall will accumulate over the next few days. This will likely create widespread avalanche activity all elevations. Storm slabs may be touchy, run far and be destructive. This is a good time to stay out of avalanche terrain.

Avalanche Summary

Observations are extremely limited at this time. A few small size 1.0 avalanches were reported from the southern part of the region yesterday. The next few days will hold a different story. I'd expect widespread avalanche activity. They may react as storm slab instabilities with potentially triggering any weaknesses lower in the snowpack.

Snowpack Summary

Up to 40cm of new snow has fallen in the southern part of the region. This has been accompanied by moderate to strong winds from the southwest. In the alpine, and treeline new wind slabs are forming lee of ridgelines and terrain features. These wind slabs are sitting on older wind slabs and may have a poor bond. At treeline I suspect there to be some patchy areas of buried surface hoar and older raincrusts down 50-60cm. These may become reactive with the new storm snow load. Snowpack depths are likely in the 60-90cm range at about 1600m and about 150 cms at 2000m.

Confidence

Good - -1

Weather Forecast

An intense system is moving across the interior ranges today bringing heavy precipitation amounts, rising freezing levels and strong ridgetop southerly-southwesterly winds. Freezing levels could rise to 1900m then fall to 800m before the next system passes. Thursday and Friday we should see freezing levels fall back to valley bottom and accompanied by steady light to moderate precipitation.

Regions covered