Boletín de aludes

Purcells

Dec 16 – 17, 2015Avalanche Canada
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Archivado · caducó 11 years ago

Peligro de aludes

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

Lo esencial

It sounds like good riding conditions out there but large human triggered avalanches are still possible. Start with small test slopes and build up slowly to bigger features.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    1–2
    Recent winds have been mainly light and variable, however, small pockets of wind slab can be found in some ridge loaded lee features.
  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–4
    A layer of buried surface hoar can be found bellow treeline, between 1400m and 1800m. It remains sensitive to human triggering. Watch out for signs of instability like wumphing to guide you through this elevation band.

Weather Forecast

THURSDAY: no new snow is expected, mainly light south winds, remaining cool, -10C at 1500m. FRIDAY: Light snow fall, up to 10cm, with the greatest accumulations in the south of the region, moderate westerly winds, still cool. SATURDAY: light snowfall, up to 5cm, again mainly in the south, light southerly winds, cool.

Avalanche Summary

Avalanche activity appears to have tapered off since the weekend.  Avalanche professionals in the field are reporting sluffing in steep terrain in response to skier traffic (aka good riding conditions) and some lingering reactive pockets of wind slab in steep lee features. No new avalanches have been reported on the layer of buried surface hoar since last week, however, people have been experiencing wumphing and other signs of instability from safe terrain as they travel between 1400 and 1800m.

Snowpack Summary

It sounds like good riding conditions out there with mainly low density snow on the surface. There is some localized wind effect in the new snow at ridgeline. About 15 to 40cm of snow sits above a crust that extends up to 1800m. The early December persistent weak layer can now be found down 30-80cm.  This layer can be found as an old sun crust on solar aspects in the alpine, or as large grained surface hoar and small facets in isolated pockets bellow treeline.  The surface hoar is mainly a problem between 1400m and 1800m, although it may extend higher in the south of Invermere. Snow pit tests on this interface have been widely variable; producing a mixture of sudden and resistant failures or no results. The mid and lower portions of the snowpack are thought to be mainly well settled.

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