Bulletin d’avalanche

Northwest Coastal

Jan 22 – 23, 2016Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Tricky conditions warrant a very conservative and disciplined approach at this time. 

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–5
    Buried surface hoar, now 60 cm deep on average, is primed for triggering. It's possible for light loads to trigger slabs even from relatively low angle slopes. Be extra cautious near treeline where surface hoar is more likely to be preserved. 

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Storm and wind slabs continue to grow. These slabs may be particularly touchy in exposed lee (W-NE) and cross-loaded terrain. 

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Saturday: Cloudy with 2-5 cm of snow. The freezing level is near 600 m and winds ease to light. Sunday: Mainly cloudy with light snow. The freezing level is around 400 m and winds are moderate from the southeast. Monday: Periods of snow. The freezing level rises to 800-1200 m and winds increase to strong from the S-SE.

Avalanche Summary

We continue to hear reports of small skier-triggered size 1-1.5 slabs and some remotely triggered slabs. Although small, these slabs are occurring on lower angle terrain (25-35 degrees) with surprising propagations. Each day we have received 5-15 cm of new snow. This incremental loading is enough to maintain tricky conditions, but not enough to "clean out" buried persistent weaknesses by causing a widespread avalanche cycle. On Tuesday and Wednesday, explosives control in areas near Bear Pass and northeast of Terrace produced numerous slab avalanches, size 2-3.5, likely failing on the January 9th interface. Some had very impressive propagations.

Snowpack Summary

We've generally seen 10-30 cm of new snow with moderate S-SE winds over the last couple days. Expect fresh wind slabs overlying older wind-affected surfaces in exposed lee and cross-loaded terrain. The January 9th surface hoar/facet layer down 50-70 cm in most places, and seems most concerning at and below treeline. Approximately 10 cm below this weakness you might find the Dec. 26/31 surface hoar layer. Reports of remote triggering, whumpfing, and sudden "pops" shears are all indications that both these layers could propagate well if triggered. Deeper persistent weaknesses buried in December have the potential to wake-up to heavy loading, rapid warming, or avalanches stepping-down.

Régions couvertes