Bulletin d’avalanche

Northwest Inland

Dec 11 – 12, 2012Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–5
    Wind slabs are likely to be found on alpine slopes and behind ridges and ribs at treeline. Storm slabs may exist in sheltered areas not affected by wind.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–6
    A deeply buried facet/crust weakness exists. While the likelihood of triggering is relatively low, the consequences could be a very large and destructive avalanche.

Confidence

Poor - Due to limited field observations

Weather Forecast

Wednesday: Light NW winds. Alpine temp -7. Light to moderate snow beginning late in the day.Thursday: Strong to gale W winds. Alpine temp -8. Moderate snow.Friday: Light S winds. Alpine temp -8. Moderate snow.

Avalanche Summary

Strong W-NW winds triggered a natural avalanche cycle on Sunday, with several slabs to size 2 failing behind cross-loaded ribs and gullies. A size 2.5 slab from the headwall above the Hankin-Evelyn area is suspected to have failed on the Nov crust/facet layer. We have no reports of avalanches during Monday night’s warming, but I wouldn’t be surprised if a natural cycle had occurred.

Snowpack Summary

Warm temperatures on Monday night led to upside-down storm snow (dense snow over lighter snow) and rain at low elevations. Wind slabs formed in the last few days may now be buried on a variety of slopes.  In the upper snowpack, surface hoar is buried at tree line in isolated sheltered areas. A November crust/facet layer near the base of the snowpack has the potential for deep releases. Snow depths are highly variable due to the influence of recent winds.

Régions couvertes