Bulletin d’avalanche

Purcells

Mar 9 – 10, 2016Avalanche Canada
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Archivé · expiré 11 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

A storm on Thursday will bring high avalanche danger to the Purcell Mountains.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    3–5
    A crust/surface hoar layer buried approximately 60 cm below the surface is triggerable by people on sleds or on skis. This layer could also avalanche naturally during stormy weather and produce large avalanches.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–4
    Storm and wind-slab avalanches are expected to run in response to new snow and wind, particularly on north through east aspects.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Thursday: 10-20 cm new snow expected with the heaviest amounts likely to be in the south of the region. Strong southwest winds up to 80 km/h expected at ridgetop. Freezing levels expected to rise to 1900 m near noon.  Friday: Dry with some clear spells. Winds becoming light southeasterly. Freezing level around 1700 m. Saturday: 5-10 cm new snow, with moderate southwesterly winds and freezing level around 1800 m.

Avalanche Summary

On Tuesday, several large (size 3) avalanches were reported from south-facing slopes near Golden. On Monday, natural avalanches up to size 3.0 and human-triggered avalanches up to size 1.5 were reported from northerly aspects, mostly in the alpine.

Snowpack Summary

30-70 cm recent storm snow overlies a prominent weak layer buried on or around Feb-27. The deepest snow amounts appear the be in the west central area near Kootenay Lake. The Feb-27 weak layer comprises surface hoar and a crust. It has been widely reported but recent snowpack test results are mixed, with some tests indicating this layer is gaining strength, while others indicating it can still fail with sudden "pop" results. A deeper weak layer from mid-February is now down 50-80cm. The early January surface hoar/facet layer is typically down 70-120cm. Triggering an avalanche on either of these layers has become unlikely but either still has the isolated potential to produce very large avalanches with a heavy trigger.

Régions couvertes