Bulletin d’avalanche

Northwest Inland

Dec 1, 2017Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

The late October crust near the base of the snowpack is reactive to rider triggers producing large avalanches. You could trigger this from a significant distance away. Heads up out there as this problem will likely persist.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Recent snow and wind have formed touchy wind slabs. Expect these slabs to be more pronounced at higher elevations and on leeward aspects. Watch for signs of wind affected snow, whumpfing and cracking.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–3
    The late October crust lies near the base of the snowpack with a thin layer of weak, sugary snow above it. This layer has been reactive to rider triggers and remote triggering has occurred.

Confidence

Low - Due to the number and quality of field observations

Weather Forecast

Friday: Cloudy with possible flurries. Strong ridgetop winds from the West. Alpine temperature -10. Freezing level 500 m and dropping.Saturday: Mix of sun and cloud. Light ridgetop winds from the North West. Alpine temperature -15. Freezing level valley bottom.Sunday: Mostly sunny with some residual cloud. Strong ridgetop winds from the North West. Alpine temperature -12. Freezing level valley bottom. Visit the Mountain Weather Forecast for more details.

Avalanche Summary

On Tuesday, skiers up Skilokis Creek area reported remotely triggering a large (Size 2.5) avalanche from 150 m away as they approached a north-facing, treeline bowl. The avalanche was triggered from a shallow snowpack area and failed on a weak facet layer just above the late October crust near the base of the snowpack. The persistent slab was 80 cm deep, 120 m wide and ran 300 m in length. The week before that, several estimated Size 2.5-3 avalanches were observed on the Kathlyn face of Hudson Bay Mountain and are also suspected to have failed on the late October crust. This "crust/facet combo" layer is capable of producing very large avalanche and is expected to remain a layer of concern for some time. Please post your observations to the Mountain Information Network. (MIN)

Snowpack Summary

Average Snowpack depths are 100-140 cm at treeline elevations, and up to 160 cm in the alpine. Approximately 30-40 cm of recent snow now overlies the supportive November 23 crust. This crust extends well into alpine elevations. Below this crust is a well settled mid pack that sits on the widespread late October crust near the base of the snowpack at all elevations. This late October "crust/facet combo" layer has been very reactive to rider triggers producing large avalanches.

Régions couvertes