Boletín de aludes

Lizard-Flathead

Dec 12 – 13, 2022Avalanche Canada
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Archivado · caducó 4 years ago

Peligro de aludes

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

Large skier-triggered avalanches have occurred in our region in the last few days!

Storm slabs and buried weak layers can surprise and create large avalanches.

Assess conditions while you travel and choose your terrain carefully. Watch and feel for signs of instability such as whumpfing, cracking, and recent avalanches.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    Buried layers of surface hoar and facets have been reactive to human triggers in recent days. Reactivity has been observed in sheltered areas at treeline, where the surface hoar may be preserved, and in wind-loaded areas at upper elevations, where a cohesive slab has been formed above.

    Recent warmer temperatures could have consolidated the top layer of fresh snow into a slab.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    1–1.5

    New snow with little wind is accumulating on a variety of surfaces that include a layer of low-density lighter snow. Warmer temperatures are expected to consolidate this new snow into a slab.

    Small avalanches in the upper snowpack could trigger deeper weak layers, creating a larger-than-expected avalanche.

Confidence

Moderate

Avalanche Summary

A group of skiers reported triggering a large avalanche, size 2, that released on the mid-November weak layer. This layer is still around and can be expected to produce avalanches if triggered in the "right" spot or by a heavier load.

Late in the day Sunday there was a report of a large size 3, skier-triggered avalanche in the Lizard Range. Three people were involved, with one fully buried. They were dug out by their companions. Details are not yet known at this time but more information will follow.

Thank you all for supporting your community and reporting in the MIN.

Snowpack Summary

Up to 30 cm of snow has fallen since Thursday. This sits on a variety of surfaces. In the alpine and at treeline, it sits mostly on wind slabs that were created by southwesterly winds that we experienced earlier this past week.

Below the 30 cm of new snow sits about 20 to 30 cm of more consolidated snow. Just below this is where our mid-November weak layer, consisting of facets and surface hoar. A widespread rain crust remains near the ground, at the treeline, and below the treeline.

At treeline, snowpack depths vary from 120 to 200 cm.

Weather Summary

Sunday Night

Mostly cloudy, up to 5 cm accumulation, winds northeast 10 gusting to 30 km/h, temperature -10 C at 1500 m.

Monday

A mix of sun and cloud, trace accumulation, winds northeast 10 gusting to 30 km/h, temperature -10 C at 1500 m.

Tuesday

Cloud in the morning with more sun in the afternoon, no accumulation, winds northwest 10 to 20 km/h, temperature -9 C at 1500 m.

Wednesday

Cloudy with sunny periods, 2 cm accumulation, winds west 10 km/h, temperature -10 C at 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Be especially cautious as you transition into wind affected terrain.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.

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