Bulletin d’avalanche

Purcells

Mar 28 – 29, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

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

Points saillants

A good time for conservative terrain choices.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    New snow and winds are likely to create touchy storm slabs, especially on features in the lee of the wind. A storm slab could fail on a deeply buried weakness, creating a surprisingly large avalanche.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

On Sunday, expect around 5 cm snow and moderate to strong SW to W winds. Snow eases to flurries on Monday, then the next pulse begins on Monday night, bringing around 5-10 cm snow with moderate to strong SW to NW winds. Freezing levels are between 1800 m and 2000 m, dropping on Tuesday to around 1500 m.  

Avalanche Summary

On Thursday and Friday, wind and warming were responsible for several natural slab avalanches up to size 3, mainly on east and north aspects above 2100 m. There was also a report of a close call, skier triggered size 2.5 slab avalanche in the Dogtooth range.

Snowpack Summary

Recent warm temps, sunny periods and high freezing levels will make surfaces moist; with some crust recovery/ development above 2000 m. Below that elevation, no significant overnight recoveries are expected. At treeline and above storm snow amounts from last weekend vary. The NW part of the region received up to 60 cm while the Dogtooth received around 30 cm and the far south received close to zero. This dense storm snow sits over the mid-March interface which consists of a series of crusts, old wind slabs, facets and surface hoar. Snow-pit tests have shown this interface to be fairly easy to trigger and likely to propagate. Below this interface is the mid-February facet/crust interface. The mid-February layer has been dormant for some time, however; in neighboring regions it has been reactive. Persistent weak layers may be suspect in shallower snowpack areas.

Régions couvertes