Bulletin d’avalanche

Sea To Sky

Jan 30 – 31, 2016Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

The new snow may not initially bond well to the previous snow surface. Give the snow a day or two to settle before pushing into bigger terrain.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–4
    Recent stormy weather has encouraged widespread cornice growth. Cornice falls can be destructive by themselves, but can also be a trigger for surprisingly large avalanches on the slope below.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    Buried persistent weaknesses may have been destroyed in most areas, but remain cautious in high elevation terrain (particularly in the north of the region) where this problem may be lingering.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    New snow may not bond well to the previous snow surface, especially in exposed lee terrain where wind slabs have developed. Also, watch for loose snow sluffing in steep terrain. 

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tonight and Sunday: Periods of snow. 5-10 cm tonight and 15-20 cm on Sunday. The freezing level is around 600-800 m. Winds are moderate from the S-SW easing to light. Monday: Cloudy with flurries and clearing. The freezing level is around 500-700 m and winds are light from the SW. Tuesday: Mainly sunny. The freezing level remains near 500 m and winds are light and variable.

Avalanche Summary

A few natural size 2-3.5 persistent slab avalanches were reported near Whistler on Friday. Some may have started as loose wet slides that stepped down and triggered deep slabs. All of these slides were from slopes near treeline (1800-2000 m). These likely occurred during the height of the storm on Thursday night. Explosives control also produced numerous size 2 storm slabs. Cooler and drier conditions should help improve stability and make triggering much less likely.

Snowpack Summary

By Sunday morning there could as much as 40 cm of dry new snow with the snow line extending down to at least 800 m. Expect fresh wind slabs in exposed lee terrain and the potential for storm slabs or loose dry avalanches. The intense storm earlier this week dropped around 80mm of precipitation throughout the region with fluctuating freezing levels. In the alpine deep and dense storm slabs formed and there was substantial cornice growth. At and below treeline the new snow likely sits on a crust or moist/wet snow. Where it still exists, the mid-January surface hoar layer is between 100 and 180 cm below the surface. The combination of heavy storm loading and warm temperatures has likely flushed out this weak layer in most areas. There is still some uncertainty regarding the sensitivity and distribution of this persistent avalanche problem, especially at high elevations in the north of the region where it remains reactive in snowpack tests.

Régions couvertes