Bulletin d’avalanche

Purcells

Feb 19 – 20, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Fri
Sat
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

We're moving from a storm slab problem to a persistent slab problem. Check out this blog post for thoughts on the current situation and strategies for the next the chapter.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    3–6
    This problem is surprising very experienced professionals and remains primed for human triggering. This meter deep slab has shown a propensity for remote triggering, a phenomenon that should become more prevalent as the slab gains cohesion.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–4
    Previously SW winds should switch to the NW Thursday. With plenty of new storm snow available for transport, fresh sensitive wind slabs will add even more complexity to an already tricky situation on wind exposed terrain features.

Confidence

Fair

Weather Forecast

Synopsis: The last of the heavy hitting storms has left the province. A quick hitting pulse racing down from the NW will cross through the region Thursday leaving some very light density snow in its convective wake. A serious eastern pacific ridge brings clearing skies this weekend. Too early to say how long its reign will last. Thursday: Freezing Level: 700m; Precip; 1/5mm - 1/8 cm; Wind: Mod, W | Strong W at ridgetop.Friday: Freezing Level: Valley Bottom; Precip: Trace; Wind: Light, NW | Mod W/NW at ridgetopSaturday: Freezing Level: Valley Bottom; Precip: Nil; Wind: Light

Avalanche Summary

An ongoing avalanche cycle continues to produce natural avalanches to size 3.5. A group of skiers triggered a size 2.5 avalanche while walking along a ridgeline in the northern potion of the region Friday. While the amount of activity is beginning to taper, large avalanches continue to be reported.

Snowpack Summary

The never ending storm has produced 60 - 120 cm of total snowfall across the region which is settling into a cohesive slab that averages a 40 - 90 cm in depth. This slab rests on a nasty persistent weak layer (Late Jan/Early Feb.) surface hoar/facet/crust combo that was formed during the month of cold clear weather. Field observations continue to report easily triggered sudden planar failures on this interface in snowpack tests. Large settlements / "whoomphs" have been reported at all elevations. Large natural avalanches have been widespread and destructive. The persistent weak layer under all the storm snow is incredibly pervasive in the region. I expect touchy conditions to remain in place longer than we're normally accustomed to. Ongoing strong winds out of the SW and W have loaded lee aspects and damaged snow at all elevations, but the effect is most prevalent at and above treeline. More strong winds in the forecast are expected only to add to this problem.Weak basal facets exist in some areas, but triggering has now become unlikely. For the most part, the mid and lower snowpack are strong and well consolidated.

Régions couvertes