Bulletin d’avalanche

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Jan 18 – 19, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

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

A cautious approach is required anywhere wind or settlement has created a cohesive slab. A weak layer of surface hoar has shown recent reactivity at treeline elevations and may be primed for human triggering.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2.5

    Previous storm snow has shown evidence of settling into a more cohesive slab over a layer of weak, feathery surface hoar crystals. In addition, increasing southerly winds are expected to redistribute the loose surface snow into fresh wind slabs. Be particularly cautious in open areas at treeline, where this weak layer of surface hoar is most likely to be preserved below these slabs.

    This MIN Report does a great job of explaining how the avalanche problem might present itself.

Confidence

Moderate

Avalanche Summary

Over the past few days, several size 1 to 2 avalanches were reported at Hankin, Ashman, and the Babines. These avalanches were easily triggered by the weight of a rider. They were sliding on a layer of weak, feathery surface hoar crystals, 20 to 30 cm below the snow surface. One of these slabs stepped down to a layer of weak, sugary, facetted crystals that were buried on December 23rd.

Snowpack Summary

20-30 cm of generally soft snow sits above a layer of surface hoar crystals in sheltered areas. If wind or warm temperatures have formed any of this snow into a slab, expect it to avalanche under the weight of a rider. See the avalanche summary for recent reports of avalanches on this layer.

A weak layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. Observations suggest it is fairly widespread, but rounding and gaining strength, and is not reactive to triggering under the current conditions.

Weather Summary

Tuesday night

Mainly cloudy with isolated flurries, up to 5 cm accumulation. Alpine temperatures drop to a low of -4 °C. Ridge wind south 40 km/h gusting to 65 km/h. Freezing level 700 metres.

Wednesday

Cloudy with snowfall in the morning and sunny breaks in the afternoon, with up to 5 cm accumulation. Alpine temperatures reach a high of -4 °C. Ridge wind southwest 25-45 km/h. Freezing level 700 metres.

Thursday

Cloudy with sunny periods. Alpine temperatures reach a high of -3 °C. Ridge wind southwest 30 km/h. Freezing level rises to 700 metres.

Friday

Cloudy with sunny periods. Alpine temperatures reach a high of -1 °C. Ridge wind southwest 30 km/h gusting to 60 km/h. Freezing level rises to 1200 metres.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Régions couvertes