Bulletin d’avalanche

South Columbia

Mar 25 – 26, 2016Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Sun
Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

There is some uncertainty if we will have sun all day, or if there may be a band of high cloud for most of the morning. Strong solar radiation may result in loose wet avalanches and natural cornice falls.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    3–5
    Natural cornice falls are likely during periods of strong solar radiation and warm daytime temperatures. Cornice falls may trigger deeply buried persistent weak layers.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    3–6
    The persistent weak layer of buried surface hoar, facets, and crusts is buried down close to a metre. This has become a low probability of triggering, but high consequence of large avalanche problem. Choose well supported terrain without convexities.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Storm slabs may continue to be easy to trigger on shaded aspects. Storm snow may release as loose wet avalanches on solar aspects during periods of clear and sunny weather.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

Mostly clear overnight with light westerly winds and freezing down to valley bottoms. On Saturday, a mix of sun and high cloud with light southwest winds and freezing levels rising to 1700 metres. Cloud and light precipitation developing by Sunday morning with freezing down to at least 1000 metres. On Sunday, cloudy with 5-8 cm of snow and freezing levels rising up to 1300 metres. Light snow and light winds continuing on Monday, before the next ridge of high pressure brings back the clear skies.

Avalanche Summary

No new reports of persistent slab avalanches. On Thursday there were numerous reports of new storm slab avalanches up to size 1.5 from various aspects at and above treeline. There was also some loose wet avalanche activity in the afternoon on Thursday when daytime warming weakened the new storm snow on solar aspects. On Wednesday we had reports of 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.

Snowpack Summary

New storm slabs have developed 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. Expect loose wet avalanches and natural cornice falls during periods of strong solar radiation and/or daytime warming.

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