Bulletin d’avalanche

South Coast Inland

Feb 25 – 26, 2020Avalanche Canada
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Archivé · expiré 7 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Avalanche danger will be a step higher in the south half of the region where more snow fell on a potential weak layer. If you're finding wind slab development or signs of instability, keep it dialed back. Let us know what you see out there on the Mountain Information Network!

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–2

    15-30 cm of recent snow, and as much as 50 cm in the Coquihalla, may overly isolated patches of surface hoar in sheltered areas at low elevations or sun crusts on solar aspects. In parts of the region that did not receive wind, the snow remains low density, unconsolidated and evenly distributed all except exposed ridgetops. Increasing winds on Tuesday are expected to accelerate slab development in lee features at upper elevations.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2.5–3.5

    In the north of the region (e.g. Duffey, Hurley, Goldbridge), a buried weak layer lingers at the base of the snowpack. The most likely place to trigger this layer is in shallow and rocky terrain. We doubt that the new loads from the present storm will be sufficient to induce pervasive avalanche activity on these layers, but as is typical with deep persistent avalanche problems, there is uncertainty.

Confidence

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

Monday night: Scattered cloud. Light to moderate northwest wind. Freezing level valley bottom.

Tuesday: Mix of sun and cloud with isolated flurries. Moderate to strong southwest wind. Freezing level 1000 -1400 m.

Wednesday: Mix of sun and cloud. Moderate southwest wind. Freezing level 1400 m.

Thursday: Mix of sun and cloud. Moderate southwest wind. Freezing level 1500 m.

Avalanche Summary

Reports of avalanche activity over the weekend were limited to loose dry and soft slab avalanches to size 1.5 in the north of the region

Snowpack Summary

15-30 cm of recent snow, and as high as 50 cm in the Coquihalla, may overly isolated patches of surface hoar in sheltered areas at low elevations or sun crusts on solar aspects. In parts of the region that did not receive wind, the snow remains low density and evenly distributed all except exposed ridgetops. In windier areas, slabs up to 50 cm deep have been observed in lee features in the alpine. Increasing winds on Tuesday are expected to accelerate wind slab development.

In the north part of the region (e.g. Duffey/Hurley/Goldbridge), a deep instability exists in the snowpack, consisting of a weak basal facet-crust complex. Sporadic avalanche activity on this layer is keeping it on our radar, with the latest report described here. In the south of the region, including the Coquihalla and Manning areas, there are no concerns about deeply buried weak layers.

Terrain and Travel

  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.
  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • In times of uncertainty conservative terrain choices are our best defense.

Régions couvertes