Bulletin d’avalanche

South Rockies

Jan 30 – 31, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Wind slabs will continue to be an issue Tuesday. They may be found lower on slopes in unusual places due to the strong winds. Wind slab avalanches will likely be reactive to rider triggers producing avalanches up to size 2.5.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    The region received up to 30cms of new snow Sunday night. Storm slabs are reported to be touchy to rider triggers.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Tuesday: Fairly zonal flow with light precipitation. Ridgetop winds 35-50km/hr from the West. Treeline temperatures near -5. Freezing levels at valley bottom. Wednesday: Ridgetop winds 20-45km/hr from the West. Treeline temperatures near -8. Thursday: Dry conditions continue through to Saturday. A ridge over BC will bring a warmer air mass to the region. Freezing levels may rise to 1200m.

Avalanche Summary

On Sunday several size 2 natural slab avalanches were seen. On Monday skier controlled, and explosive controlled avalanches were initiated up to size 2 with crown depths being 30-40cms. Monday afternoon the sun poked out and sluffing occurred on steep, rocky south facing slopes.

Snowpack Summary

The freezing level was as high as 1500m Sunday, as a result, a lot of precipitation that fell on Sunday was rain. Sunday night the region received near 30cms of new snow. Strong SW winds created stiff, yet reactive wind slabs on lee slopes. Cross-loading, and wind slabs are also found lower on the slopes and in unsuspecting terrain due to the strong push of the winds. Storm slabs have also developed at all elevations, and are reported to be touchy to rider triggers. So far the new wind slab and storm slabs are only releasing in the upper 30-40cms of the snowpack, with nothing stepping down lower. Last week 40-60cm of snow formed soft slabs over a crust/facet/surface hoar combo which has settled remarkably quickly.Deeper in the snowpack, a surface hoar layer buried in early December remains a concern, as avalanches triggered on this layer would be destructive. There may have been releases on this layer post storm but at this time nothing has been reported. It should be noted that basal facets exist in many parts of the region too.

Régions couvertes