Bulletin d’avalanche

South Rockies

Jan 20 – 21, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

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

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–4
    Wind continues to build hard slabs in the alpine and at tree line, very warm temperatures and strong solar radiation may increase the likelihood of triggering. A cornice failure or radiation sloughing in cliffs could trigger lower slopes.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Cornices may become weak and fail naturally with the strong solar radiation and warm alpine temperatures. Cornice falls are a large load that may trigger buried persistent weak layers on slopes below, resulting in very large avalanches.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–6
    Storm snow and hard wind slabs have been added to the load above buried weak layers. Deeply buried weak layers may become harder to trigger, but the consequences could be very large destructive avalanches.

Confidence

Good - Due to the number and quality of field observations

Weather Forecast

No precipitation in sight for the next few days. The ridge of high pressure continues to dominate the weather pattern blocking Pacific moisture from the Pacific Northwest.Tuesday: Nil precipitation wind SW at ridge tops, freezing level at 1500m.Wednesday: Chance of light precipitation or flurries, winds from the N-NW, freezing level to 1600m.Thursday: NIl precipitation, winds light at ridge tops, freezing level to 1500m.

Avalanche Summary

Report of a size 2.5 snowmobile triggered avalanche in steep shallow snowpack, failing to ground level. We suspect this to have failed on the Nov 30th surface hoar, then stepping down to the basal facets ( surface hoar). Areas of shallow snowpack are of special concern, as well as areas where there is a hazard from above such as cornices or steep south facing cliffs. High temperatures at upper elevations may increase the chance of triggering from surface sluffing or cornice failure.

Snowpack Summary

Extensive wind transport and wind slab development has occurred in all areas of the region. Recent storm snow varies from 40-70 cm across the region and in some alpine areas storm slabs are more than a metre thick. Persistent weak layers of buried crusts/facets/surface hoar continue to be a concern, and may have been the failure plane for recent large natural avalanches. Surface facetting and surface hoar growth throught the forecast region on northerly and protected aspects. Strong solar radiation and above-freezing temperatures producing sun crust on solar aspects.

Régions couvertes