Bulletin d’avalanche

Banff Yoho Kootenay

Feb 5 – 6, 2019Parks Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Increased reactivity of the Jan 17 surface hoar/crust layer is due to recent loading of storm snow. Distribution is spotty, so dig down to verify if this layer is present in your local area.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2.5
    Recent winds have redistributing the storm snow in the alpine and created fresh windslabs in lee areas. These slabs could be up to 70cm deep.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2.5
    The Jan 17 layer is a combination of Surface Hoar and/or a melt freeze crust. Since the recent storm, it has become reactive to skier traffic and can generally be found down 50cm. Dig down, look and test this layer at tree line and below.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    The new snow load may start waking up the deep persistent facet weakness down 80-160 cm. This is of greatest concern in shallow snowpack areas where the basal facets are weakest.

Weather Forecast

A arctic ridge of high pressure will linger in the bulletin region for the remainder of the week. Temperatures will remain frigid, with evening lows down to -30. A temperature inversion has set in at higher elevations. Light winds, sunny skies and temperatures in the low negative teens will make the alpine the place to be.

Snowpack Summary

Recent snow and wind have created wind slab on lee alpine slopes. At treeline elevations, up to 65cm of snow sits over the Jan.17 surface hoar. In shallower areas weak facets and depth hoar exist below the Dec 10 interface. In deeper snow packs this basal weaknesses is less pronounced.

Avalanche Summary

No new avalanches reported or observed today. Evidence of a widespread natural avalanche cycle to size 2.5 from the weekend is visible at tree line and above. Recent reports have noted skier triggered avalanches to size 1.5 on the Jan 17 SH layer. As the recent storm snow continues to settle we can expect larger propagations on this weak layer.

Confidence

Régions couvertes