Boletín de aludes

South Rockies

Feb 15 – 16, 2012Avalanche Canada
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Archivado · caducó 15 years ago

Peligro de aludes

Fri
Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    1–2
    Although thin, fresh wind slabs could quickly become twitchy where they devolop above a suncrust.

  • Cornices

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    1–3
    Cornices are large, unsupported and may be a trigger for a large avalanche on the slope below.

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    3–6
    Deep and destructive persistent slab avalanches are unlikely, but a large trigger may activate this weakness on a steep, rocky & unsupported area with a shallow snowpack.

Confidence

Good

Weather Forecast

The general pattern of a dominating high pressure ridge with weak disturbances passing through continues. Thursday should see strong NW or W winds, and a few cm of snow late in the day. Friday should be sunny & warm in the afternoon, well below freezing overnight. Saturday another disturbance is expected with a few more cm of snow and freezing level around 1000m.

Avalanche Summary

Only small avalanches were observed, mostly loose snow in steep terrain (I'm guessing solar triggered) and small slabs lee of ridges (but these are likely a day or two old). Loose surface snow may be susceptible to sluffing on steep slopes but shouldn't be too destructive unless terrain traps are in the runout. Deep persistent slab avalanches remain possible with heavy triggers in shallow rocky snowpack areas on unsupported slopes.

Snowpack Summary

On sunny slopes (SE, S, or around toward W facing slopes) Wednesday's sun created a crust. On shady slopes a new layer of surface hoar formed overnight Tuesday. Also on shady slopes immediately below the surface (hoar) is 5 to 10 cm of recent snow sitting on a second surface hoar layer, which in turn sits on sugary facetted snow. One report showed the feathery crystals of surface hoar around 4 cm long. All the crusts and surface hoar will need watching once it snows. Below these upper layers a well settled and strong snowpack sits on weak basal facets and depth hoar, which seem to be fairly widespread throughout the region. This deep persistent weakness was recently activated by warm temperatures, but cooler temperatures have once again reduced the sensitivity to triggers. Highly unpredictable glide cracks are also opening up, primarily on slopes with smooth ground cover. These full-depth gaping 'crevasses' could release without warning or act as a significant terrain trap.

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