Bulletin d’avalanche

South Columbia

Dec 17 – 18, 2018Avalanche Canada
Voir sur la carte
Archivé · expiré 8 years ago

Danger d’avalanche

Wed
Thu
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
Ouvrir la carte complète

Points saillants

Another storm tonight and tomorrow will keep danger elevated for Tuesday.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    Up to 120 cm of new snow sits on a weak layer of facets (sugary snow) surface hoar (feathery crystals) and sun crust (on south facing slopes). Wind loaded pockets could have 200+ cm of snow over this layer.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–2.5
    Storm and wind slabs are likely to form on steep slopes in lee (downwind) areas. The chance of storm slabs increases with the amount of new snow and the amount of wind.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

MONDAY NIGHT: 5-15 cm new snow expected. Strong southwesterly winds.TUESDAY: 10-15 cm additional new snow with freezing level around 1400 m. Strong southwesterly winds.WEDNESDAY: 2-4 cm new snow. Freezing level around 1400 m. Moderate westerly winds.THURSDAY: 5-10 cm new snow, increasing through the day. Freezing level around 1500 m. Moderate southeasterly winds.

Avalanche Summary

Numerous natural and explosives triggered avalanches to size 3.5 and human triggered avalanches to size 2 have been reported in the region daily since Wednesday, December 12. Many of these avalanches were triggered from a distance (remote triggered).A skier was caught in an avalanche on Sunday on a west aspect at around 2000 m on a small slope, which released at a depth of 50 cm on buried surface hoar.

Snowpack Summary

70-120 cm of recent storm snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals) and a sun crust (on south aspects). Strong to extreme winds have promoted widespread slab formation.Another weak layer of surface hoar and sun crust that formed in mid November is up to 120 cm below the surface. This layer is most likely to be a problem in areas where the surface hoar sits on the sun crust. This combination is most likely found on steep, south facing slopes at treeline. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in large avalanches.At the base of the snowpack is a crust that formed near the end of October. Concern for this layer is dwindling but it may still be worth considering in places such as steep, rocky, alpine terrain, especially where the snowpack is shallow. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer.

Régions couvertes