Boletín de aludes

Northwest Inland

Jan 29 – 30, 2021Avalanche Canada
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Archivado · caducó 6 years ago

Peligro de aludes

Sun
Mon
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Lo esencial

Moderate southwest wind will form fresh wind slabs and make it trickier to recognize older slabs which may still be reactive in the alpine. 

Problemas de aludes

  • Wind Slabs

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

    Moderate southwest wind on Friday will redistribute loose snow where available and form fresh wind slabs in lee terrain features on northerly and easterly aspects. Older wind slabs were formed on westerly aspects on Wednesday and may still be reactive.  

    Wind and soft slabs will be particularly touchy anywhere they overlie surface hoar that was reported to be widespread in many sheltered areas. 

    Cornice failures from above may trigger an otherwise stubborn deeper wind slab in addition to being a hazard outright.

Confidence

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

THURSDAY NIGHT: Clear with periods of clouds, light southwest wind, treeline temperature -24 C.

FRIDAY: Mainly cloudy, up to 5 cm new snow, moderate southwest wind, treeline temperature -15 C. 

SATURDAY: Mix of sun and clouds with isolated flurries, light southerly wind, treeline temperature -16 C.

SUNDAY: Mainly cloudy with isolated flurries, light southerly wind, treeline temperature -12 C.

Avalanche Summary

Fresh small wind slabs and sluffing on steep alpine slopes was reported on Tuesday. Isolated large avalanches failed during the weekend storm on recently buried surface hoar in the southwest of the region where recent snowfall amounts were on the higher end (up to 15 cm). A few cornice failures were observed late last week.  

Sporadic deep persistent slab avalanches were reported 1-2 weeks ago (triggered with heavy loads such as explosives and cornices), but deeper weak layers appear unreactive under the current conditions.

Snowpack Summary

5-20 cm recent low density snow has buried surface hoar, which was reported as widespread below treeline and isolated at sheltered treeline and alpine locations. In some areas this new snow was redistributed by easterly winds on Wednesday and formed isolated wind slabs or soft slaps. A buried sun crust can be found on steep solar aspects. The new snow sits on widespread wind scoured surfaces, older wind slabs in alpine and exposed treeline locations and open wind effected areas below treeline. A thick crust exists near the surface below 1000 m. 

The lower snowpack has two decomposing crust layers that have been causing a deep persistent slab problem for most of the past month. The upper crust is 70-140 cm deep in the Smithers area and continues to show occasional hard sudden results in snow pits. The deeper crust at the bottom of the snowpack continues to be a problem in shallow ranges like the Babines. These layers should be unreactive under the current conditions, but shallow rocky slopes should still be carefully assessed and approached with caution. 

Large cornices are weakening with cold temperatures.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Make observations and assess conditions continually as you travel.
  • Caution around slopes that are exposed to cornices overhead.

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