Bulletin d’avalanche

Kootenay Boundary

Jan 11 – 12, 2013Avalanche Canada
Voir sur la carte
Archivé · expiré 14 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
Ouvrir la carte complète

Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–5
    Shifting winds have formed wind slabs 15 - 50 cm in depth on all aspects in the alpine.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–4
    Around 50 cm of settled storm snow rests on a variety of weak surfaces. This interface is weakest at and below treeline.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Light winds out of northwest.  Freezing level at valley bottom.  No significant snowfall. 1500m temp: -10Sunday: Light winds out of northwest. Freezing level at valley bottom.  No significant snowfall.  1500m temp: -10Monday: Moderate W winds at ridgetop in the AM, increasing to strong W after lunch.  Freezing level at valley bottom.  Isolated flurries, no significant accumulation.Tuesday:  Freezing level forecast to rise to 2000+m

Avalanche Summary

Widespread avalanche cycle at and below treeline to size 1.5 on Thursday.  Explosive control work (large trigger) initiated avalanches to size 2.5 on SE through E facing slopes around 2000m.

Snowpack Summary

10 cm of light density snow fell Thursday adding to the 60 cm of rapidly settling storm snow that rests on the January 4th interface which consists of small facets, surface hoar (up to 12mm) in sheltered treeline and below treeline areas and sun crust on steep south and west facing slopes. The bonds with the facetted snow are improving while the surface hoar &/or sun crust interface is weak.  Recent tests show Resistant Planar shears on this layer in the alpine, but easy/sudden shears persist at and below treeline.Previous SW winds redistributed the new snow (dramatically in some areas) to create widespread wind slabbing on lee and open features in the alpine and exposed treeline. Where the wind has been strongest, wind slabs are much lower on slopes than normal.The midpack is well bonded and strong. The November 28 surface hoar is still being found in isolated, sheltered below treeline locations buried 120cm. The deep crust/facet combo from early November still exists and concern remains (although unlikely) for triggering this layer from a shallow spot or with a heavy load.

Régions couvertes