Boletín de aludes

South Coast Inland

Feb 7 – 8, 2020Avalanche Canada
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Archivado · caducó 7 years ago

Peligro de aludes

Sun
Mon
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Lo esencial

Strong southwest wind will redistribute the recent snow and form wind slabs in lee terrain features at treeline and in the alpine. Rising freezing levels might weaken the upper snow pack at lower elevations. 

Problemas de aludes

  • Storm Slabs

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

    The new snow will be redistributed by strong south wind and form sensitive wind slabs in lee terrain features in the alpine and at treeline. The avalanche danger will increase with increasing snowfall amounts in the afternoon. 

    In the south of the region the freezing level will rise to 1300 m during the day and the precipitation will turn from snow to rain weakening the snow pack.

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2.5–4

    Although the likelihood of triggering a deep persistent slab avalanche has reduced, doing so would result in a large and destructive avalanche. These layers do not pose an avalanche problem in the south half of the region.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

Thursday Night: Mix of clouds and clear skies, accumulation up to 5 cm in the south of the region, light to moderate northwest wind, alpine high - 5 C, freezing level 800 m. 

Friday: Flurries, accumulation 5 cm in most parts of the region and 10 cm in the south, strong southwest wind, alpine high -4 C, freezing level 1000 m in the north of the region and 1300 m in the south.

Saturday: Mix of sun and cloud, accumulation up to 5 cm in the north and 20-30 cm in the south of the region, light to moderate northwest wind, alpine high -4 C, freezing level 1000 m.

Sunday: Mix of sun and cloud, light to moderate northwest wind, alpine high -3 C, freezing level 1000 m.

Avalanche Summary

Numerous small (size 1) natural slab avalanches were observed below treeline which released within the recent storm snow and were very soft. Several small (size 1) and one large (size 2) loose dry avalanche were reported. 

The deep persistent slab avalanche activity observed during last weekend's storm in the northern portion of the region seems to have tapered off. Although the likelihood of triggering has reduced there is still concern for deep releases in that part of the region.

Snowpack Summary

The new snow sits on a variety of surfaces. Extreme southwest wind during the storm last weekend has scoured windward aspects, formed deep loaded pockets in alpine lees and contributed to rapid cornice growth. Below 1800 m, snow overlies a crust and tapers with elevation.

In the north part of the region (ie. Goldbridge/Duffey/Hurley), a few deep instabilities exist in the snowpack, including a weak basal facet crust complex. This has been the failure plane in ongoing reports of very large, deep persistent avalanches.

The south of the region, including the Coquihalla and Manning areas, currently have no concerns about deeply buried weak layers.

Terrain and Travel

  • Watch for avalanche hazard to increase throughout the day.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.

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