Bulletin d’avalanche

South Columbia

Mar 23 – 24, 2016Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Fri
Sat
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

New snow and strong winds overnight will increase the avalanche danger. New snow may release as loose wet avalanches when temperatures rise during the day.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    3–5
    Cloud cover and reduced solar may reduce likelihood, but forecast new snow and wind may increase the load on fragile cornice structures. Avoid slopes below cornices and chutes with corniced entrances.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    Sudden planar results in snowpack tests suggest that triggering this layer may result in wide fracture propagations and large avalanches. Avoid convex un-supported terrain features.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Forecast new snow and wind are expected to develop new storm slabs at all elevations. Moist snow below treeline may release as loose wet avalanches during daytime heating.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

10-20 cm of new snow overnight with higher amounts possible in western upslope areas. Freezing levels staying above 1300 metres with moderate to strong southwest winds. Another 5-10 cm of snow during the day on Thursday as freezing levels rise up to 1500 metres with moderate westerly winds. Some convective flurries on Friday morning with a freeze down to at least 1000 metres. Becoming mostly sunny during the day on Friday with light northwest winds and freezing levels climbing up to 1700 metres. Freezing down to 1000 metres by Saturday morning, with a mix of sun and cloud during the day.

Avalanche Summary

No new reports of persistent slab avalanches on Monday or Tuesday. Loose wet solar induced activity in most areas up to size to size 2.0, as well as some thin wind slabs in the high alpine on shaded aspects. On Sunday we had reports of natural cornice falls up to size 3.0 that triggered persistent slab avalanches on the slopes below, and solar triggered persistent slab avalanches up to size 2.5 in the alpine from slopes steeper than 40 degrees. On Saturday cornice fall produced avalanches to size 3 on north and northeast facing features between 2000 and 2400 m, failing on the late February persistent weak layer. Small natural storm and wind slabs were also reported on northwest, northeast and east facing slopes between 2100 and 2400 m.

Snowpack Summary

Forecast new snow and wind is expected to develop new storm slabs above a mix of surfaces, including crusts on solar aspects, moist snow up to treeline, and dry snow or recent wind slabs in the alpine on shaded aspects. Cornices continue to be described as large and fragile. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60 to 110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. New storm loading above the buried persistent weak layer may increase the likelihood of triggering large avalanches.

Régions couvertes