Bulletin d’avalanche

Purcells

Jan 22 – 23, 2020Avalanche Canada
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Archivé · expiré 7 years ago

Danger d’avalanche

Fri
Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Use caution as you transition into wind exposed terrain. Avalanches are possible where wind slabs have formed.

Problèmes avalancheux

  • Wind Slabs

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

    Wind slabs may be touchy in lee terrain features, particularly near ridges

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3.5

    Triggering large, deep persistent slab avalanches is a low likelihood but high consequence problem that is most likely in shallow, rocky start zones.

Confidence

Moderate - Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.

Weather Forecast

TUESDAY NIGHT - Cloudy with clear periods and isolated flurries / southwest wind, 20-40 km/h / alpine low temperature near -8

WEDNESDAY - Cloudy with sunny periods and isolated flurries / southwest wind, 10-25 km/h / alpine high temperature near -8

THURSDAY - Cloudy with sunny periods and isolated flurries / southwest wind, 25-50 km/h / alpine high temperature near -2 / freezing level 1300 m

FRIDAY - Flurries, 5-10 cm / southwest wind, 20-40 km/h / alpine high temperature near -2 / freezing level 1500 m

Avalanche Summary

On Sunday and Monday there were a few natural and cornice triggered avalanches up to size 2.5.

Numerous large (size 2) wind slabs were triggered by humans and explosives on Saturday. They were generally 10 to 40 cm deep and occurred at treeline and alpine elevations.

A couple of deep persistent slabs were triggered by explosives. They were large (size 2) and occurred in the alpine, scrubbing to the ground.

Snowpack Summary

Around 15 cm of recent snow and strong southwest wind has produced wind slabs in lee terrain features, particularly near ridges.

A layer of surface hoar that formed in late December appears to be less reactive than it was a week ago and can be found 70 cm deep around Golden, 30 cm deep around Invermere, 70 cm deep around Kimberley, and 100 cm deep along Kootenay Lake.

As usual for the Purcells, the base of the snowpack contains basal facets and it remains possible to trigger these deep weak layers in shallow rocky start zones or from a heavy trigger such as a cornice fall or explosives.

Terrain and Travel

  • Avoid freshly wind loaded terrain features.
  • Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.

Régions couvertes