Bulletin d’avalanche

South Coast Inland

Jan 25 – 26, 2020Avalanche Canada
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Archivé · expiré 7 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

Triggering avalanches remains likely where new snow and wind has formed storm slabs, especially at higher elevations.

Problèmes avalancheux

  • Storm Slabs

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

    New snow, wind, and mild temperatures formed slabs, especially at higher elevations and wind affected terrain. 

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3

    Weak layers in the northern part of the region will be stressed by the storm, increasing the likelihood of large deep persistent slab avalanches. Two layers have been a concern in the north including a 100 cm deep surface hoar layer in sheltered areas around treeline and weak, facetted snow near the bottom of the snowpack in shallow rocky start zones at higher elevations.

Confidence

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

Weather Forecast

FRIDAY NIGHT: Isolated flurries. Alpine low temperature -6 C. South wind, 15-40 km/hr. Freezing level 1000 m.

SATURDAY: Scattered wet flurries, 5 cm. Alpine high temperature -4 C. South wind 20 km/hr. Freezing level 1500 m.

SUNDAY: Snow, 15-30 cm. Alpine high temperature -3 C. South wind 20-55 km/hr. Freezing level 1400 m.

MONDAY: Scattered flurries, 5-10 cm. Alpine high temperature -4 C. Southwest wind 20 gusting to 50 km/hr. Freezing level 1200 m.

Avalanche Summary

On Friday, small loose wet avalanches failed on south aspects at lower treeline and below treeline elevations.

A large (size 2) deep persistent avalanche failed naturally sometime between Thursday and Friday on north-northwest aspect at 2150 m in the Duffey Lake area. Weak faceted grains and crusts near the base of the snowpack have periodically produced avalanches and continue to be a concern with additional loading from new snow and wind.

On Thursday, small (size 1) storm slab avalanches failed naturally on northerly aspects. Additionally, a machine triggered a size 2 avalanche on a steep slope below a road at 1800 m. Small (size 1-1.5) wet loose avalanche activity was reported below treeline.

Snowpack Summary

New snow, wind and warm temperatures have contributed to storm slab development at treeline and above. As winds impact new, dry snow expect to see scouring and wind loading at upper elevations. Below 1600 m, rising freezing levels and rain produced moist surface snow and rapid snowpack settlement.

There are currently no concerns about deep weak layers in the south of the region (e.g. Coquihalla). There have been two layers of concern in the northern half of the region (e.g. Duffey, Hurley). One is a weak layer of surface hoar buried about 100 cm deep that professionals are tracking at treeline in sheltered areas. The other is weak faceted grains and crusts near the bottom of the snowpack, that is most likely to be triggered in shallow rocky start zones.

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be alert to conditions that change with elevation.
  • Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.

Régions couvertes