Bulletin d’avalanche

Yukon

Jan 16 – 17, 2025Avalanche Canada
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Archivé · expiré 2 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
Sans niveau
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Points saillants

Stick to simple terrain and avoid overhead slopes because the persistent slab avalanche problem is alive and well.It's possible to remote trigger very large avalanches from long distances

 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    Fresh and reactive wind slabs exist. North through east slopes are very loaded with deep deposits of snow.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–3.5

    A layer of facets over a crust buried 60 to 100 cm deep and if triggered will produce large and destructive avalanches.

Confidence

Moderate

Avalanche Summary

On Wednesday, the Yukon team remotely triggered a large (size 3) persistent slab avalanche from 100 m away near Bryant Lake. It was triggered from flat terrain at the col on a ENE aspect at 1500 m. Crown depth is 100 to 200 cm, the width is 400 m and the length is 400 m. It ran on the December facet/ crust interface. Visibility on Wednesday showcased a natural avalanche cycle up to size 3 during the recent storm.

Human-triggered avalanches remain likely on Thursday.

Snowpack Summary

35 cm to 60 cm of storm snow continues to be redistributed by strong southwest winds building thick and reactive wind slabs on leeward slopes. A thin melt-freeze crust exists at lower elevations that saw rain.

A persistent weak layer consisting of a crust with 20 cm of faceted snow above it is buried 60 to 100 cm, and extends up to 1750 m. Snowpack testing has shown moderate results with a sudden collapse behaviour. This indicates that human triggering is possible.

Total snow depths are around 160–190 cm at treeline.

Weather Summary

Wednesday Night

Cloudy with clear periods and isolated flurries up to 5 cm. 15 to 40 km/h northwest ridgetop wind. Treeline temperature -12 °C.

Thursday

Mix of sun and cloud. 10 gusting to 40 km/h northeast ridgetop wind. Treeline temperature -12 °C.

Friday

A mix of sun and cloud. 20 km/h west ridgetop wind. Treeline temperature -15 °C.

Saturday

A mix of sun and cloud.10 to 25 km/h southwest ridgetop wind. Treeline temperature -15 °C. Possible above freezing layer.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • In times of uncertainty, conservative terrain choices are our best defense.

Régions couvertes