Bulletin d’avalanche

South Coast

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

Danger d’avalanche

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

Destructive persistent weak layers should still be on your radar if you're heading to the north of the region. Also, keep an eye on new snow amounts and how well this new snow is bonding.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    Recent stormy weather has encouraged widespread cornice growth. Large 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
    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 initially bond well to the previous snow surface, especially in exposed lee terrain where fresh wind slabs develop. Also, watch for loose dry sluffing in steep open terrain. 

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tonight and Sunday: Periods of snow. 5-10 cm tonight and 10-15 cm on Sunday (snow looks heaviest in the northern part of the region). The freezing level is around 600-900 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

On Thursday, slab avalanches to size 3.5 were observed on a variety of aspects and elevations. These occurred in response to heavy storm loading from rain and snow. The mid-January surface hoar was the suspected culprit in many of these avalanches. Of note was a size 4 slab avalanche in Steep Creek in the Duffey Lake area. Moving forward, cooling will likely put a cap on persistent slab avalanche activity, except on higher elevation slopes in the north of the region where reactivity is expected to persist. Forecast wind and snow could create fresh touchy wind slabs in exposed lee and cross-loaded terrain this weekend.

Snowpack Summary

Convective precipitation delivered variable new snow amounts to the region on Friday. In the south, as much as 40 cm of snow may have accumulated, while further north there may have only been 10-15 cm. This new snow likely rests on moist/wet snow or a hard rain crust depending on elevation. A storm earlier in the week created deep and dense storm slabs in high elevation terrain and cause substantial cornice growth. Where it still exists, the mid-January surface hoar layer is between 60 and 130 cm below the surface. The combination of heavy storm loading and warm temperatures has likely flushed out this weak layer in many areas; however, I would still exercise caution on higher elevation slopes in the north of the region where continued reactivity at this destructive interface is likely to persist.

Régions couvertes