Boletín de aludes

South Columbia

Jan 4 – 5, 2022Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

Thu
Fri
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Lo esencial

Reactive storm slabs are widespread at all elevations. Evaluate terrain features carefully. Avoid large unsupported slopes and navigate wind loaded features cautiously. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    2.5–3.5

    Weak faceted grains above the early December crust found around 80 to 150 cm deep is most concerning in areas where the snowpack thins at treeline elevations. 

    Avoid likely trigger spots such as steep, rocky start zones. Smaller avalanches have the potential to step down to deeper weak layers. Read more about it here.

    A layer of weak feathery surface hoar is buried 40-60cm in wind sheltered terrain, still reactive to skier triggers. Take care in cut blocks and sheltered openings at treeline and below. 

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely - Very Likely
    Tamaño
    1–2

    South/southwest winds will create deeper deposits in wind loaded features.

    Larger avalanches could be triggered in sheltered treeline terrain features where slabs sit over a touchy surface hoar layer.

Confidence

High - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

MONDAY NIGHT: Up to 5-10cm of snow, tapering off in the afternoon. Alpine high of -8 with light southwest winds.

TUESDAY: Chance of flurries with light southerly winds. Alpine high of -12. 

WEDNESDAY: Clearing skies, isolated flurries. Light southwest winds. Alpine high of -15. 

THURSDAY: Light snowfall begins in the morning with increasing southwesterly winds. Temperatures begin to rise with alpine highs of -12. 

Avalanche Summary

On Sunday, several natural and skier triggered slabs were observed in wind loaded features at treeline and above to size 2. 

Cornice falls have triggered numerous slabs this week, as they land on the slopes below. Navigate around cornices carefully, both on ridgelines and on the slopes below them with care - they are able to effect deeply buried weak layers. 

Several large and destructive persistent slab avalanches have been naturally and skier triggered in the Selkirks over the last week up to size 3.5, failing on the early December crust/facet interface. Each had wide propagation and ran several hundred metres. The avalanches were all triggered in a rocky and thin area.

Snowpack Summary

Up to 40cm of low density storm snow has fallen this week and has been redistributed into wind loaded features at treeline and above by strong southwest winds. 

A layer of weak surface hoar crystals can be found 30-50cm deep in sheltered terrain features at alpine and treeline elevations, and in open features like cut blocks below treeline. 

The crust formed by the early December rain event sits 100-150cm deep and is found up to 2400 m. Faceted grains sit above, creating a weak interface that is still reactive to human triggers. This layer is most reactive at treeline, and in areas where the snowpack thins and the weak interface is much closer to the surface. This layer has the potential to produce large and destructive avalanches if triggered. Natural and skier triggered avalanches have occurred on this layer in the last week, to size 3.5 

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Avoid convexities, steep unsupported terrain and rocky outcroppings.

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