Bulletin d’avalanche

Banff Yoho Kootenay

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

Danger d’avalanche

Sun
Mon
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

A heavy snow fall (up to 70 cm) has overloaded a weak snowpack. Stay clear of avalanche terrain. Slopes that have not avalanched are ripe for human triggering.

Problèmes avalancheux

  • Loose Dry

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2.5
    With winds tapering tomorrow, there should be fewer loose dry avalanches, but they will still be a concern given the amount of snow we have received. Any increase in wind could trigger loose dry avalanches which in turn can trigger deeper avalanches.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1.5–3
    Up to 70 cm of storm snow has formed a touchy storm slab at all elevations. Numerous slopes & cutbanks below treeline have avalanched wall to wall or remain poised for human triggering.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    2–3.5
    The Dec. 10th layer of facets & surface hoar down 100-150 cm has been overloaded by recent storm snow. The snow pack needs time to adjust, be very conservative with route choices this weekend and avoid overhead exposure.

Weather Forecast

The snowfall tapers off tonight & winds should also drop off slightly. For Saturday, there is a break in the weather with cloudy skies & cooler temperatures expected. A minor front crosses the region on Sunday bringing light flurries & higher winds. Beware - any additional load from wind transport may trigger slopes that have not yet avalanched.

Snowpack Summary

Up to 70 cm of storm snow with moderate to strong WSW wind has overloaded the persistent weak layers. In thicker snow pack areas, the Dec. 10th weak layer of facets & depth hoar is now down 100-150 m with a stronger snowpack below. In thin snowpack areas, the Dec.10th layer is mixed in with the basal facets and October crust.

Avalanche Summary

Over the past 24 hours, there has been a avalanche cycle up to size 3.5, some ran full path, and many have scrubbed to ground. Many steeper features at treeline & below have also avalanched. The natural activity should taper, but slopes will remain hair trigger with any further wind loading or by recreationalists on or near a slope.

Confidence

Régions couvertes