Bulletin d’avalanche

Banff Yoho Kootenay

Feb 25 – 26, 2025Avalanche Canada
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Archivé · expiré 2 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré

Points saillants

The snowpack is gradually adjusting to the new load from the recent storm. While minimal natural avalanche activity has been observed since the storm, several human-triggered avalanches have been reported over the past two days. Conservative terrain choices will be the best risk mitigation strategy over the next few days.

Problèmes avalancheux

  • Persistent Slabs

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

    10-30 cm of new snow and strong S-SW winds have loaded lee areas at treeline and above with new slabs up to 60 cm deep. This is sitting on a weak layer of facets, surface hoar or sun crust. Human triggering will remain likely in steep or wind loaded terrain for the next few days.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1.5–2.5

    The recent storm has added load to an already shallow and weak snowpack. With this additional weight, we suspect there may be a reawakening of this problem in isolated areas. Areas of concern include thin, shallow, and rocky slopes.

Confidence

Moderate

Avalanche Summary

The local ski hills reported triggering several avalanches today using explosives and ski cuts, up to size two. One notable observation was a ski cut that initiated a size 2 deep persistent slab, 1 meter deep.

A skier accidental size 2 wind slab that likely propagated on the facets under the storm snow was observed on Twin Cairns Sunday, with one person going for a rocky ride but ending up relatively unscathed.

Snowpack Summary

10-30 cm of new snow has fallen with mild temps and strong S-SW winds helping to form new wind and storm slabs. This new snow sits over a layer of weak facets, surface hoar or sun crust from the cold snap.

The mid-pack is generally weak facets, while depth hoar and crusts form an even weaker base. The snowpack is the weakest in eastern areas where snow depths are low. In these areas, the basal weaknesses should be carefully considered.

Weather Summary

A southwest flow may bring light flurries to the forecast region on Tuesday, with snow accumulation ranging from 0 to 5 centimeters by Wednesday. Ridgetop winds are expected to be moderate, coming from the W-SW. Daytime high temperatures will be around +5°C at the valley bottom on Tuesday.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • Avoid freshly wind-loaded features, especially near ridge crests, rollovers, and in steep terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Loose avalanches may step down to deeper layers, resulting in larger avalanches.

Régions couvertes