Bulletin d’avalanche

Kootenay Boundary

Feb 25 – 26, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–6
    The presence of weak layers buried in the upper snowpack means there is a risk of triggering surprisingly large slabs.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–5
    Loading from new snow and wind has increased the avalanche danger, especially where the wind has shifted snow into slabs behind terrain breaks like ridges and ribs.

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Tuesday and Wednesday: Possible sunny breaks with isolated flurries, winds light from the northwest and alpine temperatures -5. Freezing level rising to 800m on Tuesday.Thursday: Light snow, winds light from the southwest and alpine temperatures of -6. Freezing level 900m.

Avalanche Summary

A natural cycle began on Friday and continued on Saturday, with several slabs to size 2.5 failing on all aspects. Many were triggered by wind-loading. They failed within the storm snow or on the mid-Feb surface hoar or crust layers.

Snowpack Summary

In much of the region, up to 65 cm recent snow overlies weak interfaces buried in mid-February (mainly surface hoar/ sun crust layers). The storm slab above these interfaces has the potential for wide propagations and surprisingly large avalanches, especially where winds have shifted the snow into slabs in the lee of terrain breaks. A thin freezing rain/rime crust formed on Friday, which is now buried by about 15 cm snow. Snow forecast overnight Sunday and on Monday will add to these storm slabs.In the Rossland Range, surface hoar which was buried mid-week is 20-30 cm down and exhibits easy, sudden results in snowpack tests. As more snow builds over this layer, it could become touchy.Older snowpack weaknesses buried in the upper snowpack (Feb 4th and Jan 23 surface hoar/facet/sun crust layers) are still being tracked by professionals. There is some potential for triggering one of these deeper layers with a large trigger like an avalanche in motion, or from a thin-spot trigger point. The lower snowpack is generally well settled.

Régions couvertes