Bulletin d’avalanche

South Rockies

Jan 17 – 18, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
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
    Strong winds have created hard wind 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 may trigger lower slopes.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Cornices may become weak and fall off naturally due to strong solar radiation and forecast warm alpine temperatures. Cornice falls are a large load that may release 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
    Recent 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 are very large destructive avalanches.

Avalanche Summary

1 size 2.5  snowmobile triggered avalanche in steep shallow snowpack, also several size 2 natural avalanches in the past 24 to 48 hrs. and ,most likely triggered by radiation heating, failing to near ground level. 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.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overnight: Temperatures are expected to rise overnight at higher elevations, and drop down to close to freezing at 1600 metres. Upper elevation winds should be moderate South Westerlies Saturday: Clear, sunny, and very warm in the alpine with light Westerly winds. Expect +5 degrees in the alpine with strong solar radiation.Sunday: .Temperatures begin to cool down late Sunday with variable light winds. Freezing level around 1400m.

Snowpack Summary

Expect extensive wind transport and wind slab development in all areas of the region. Recent storm snow varies from 40-70 cm across the region and I suspect that in some alpine areas storm snow has been transported into slabs that 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. Forecast very warm temperatures may result in loose wet avalanches or cornice falls that may trigger the persistent weak layers or the basal depth hoar. Strong solar radiation combined with above freezing temperatures in the alpine could create very touchy triggering on Southerly aspects.

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