Boletín de aludes

Northwest Inland

Mar 7 – 8, 2022Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

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

Extreme west wind will continue to develop fresh wind slabs where loose snow is available for transport and grow cornices. It is uncertain whether the buried weak layer is reactive to human triggers. 

Problemas de aludes

  • Wind Slabs

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

    Extreme west wind continues to redistribute loose snow where it is available and build fresh wind slabs. Wind slabs can be found in lee terrain features below ridge crests and might be found farther down slope than expected due to the strength of the wind.

    A persistent weak layer is buried 40-60 cm deep and consist of a melt-freeze crust. There is uncertainty whether this layer is reactive to human triggers. A triggered wind slab might step down to this layer and result in a larger avalanche than expected.

  • Cornices

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

    Cornices are growing with extreme wind. Avoid slopes with cornice hazard above. Keep in mind that firm cornices can pull back into flat terrain at ridgetop if they fail. 

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Sunday night: Mostly cloudy, up to 2 cm snow, extreme west wind, alpine low -5 °C, freezing level dropping to 500 m. 

Monday: Mix of sun and cloud, trace of new snow, moderate northwest wind, alpine high -7 °C, freezing level around 800 m.  

Tuesday: Mainly sunny, light to moderate northeast wind, alpine high -12 °C, freezing level at valley bottom.

Wednesday: Mix of sun and cloud, moderate northerly wind, alpine high -8 °C, freezing level at valley bottom. 

Avalanche Summary

A large (size 2) slab avalanche that was likely triggered by a failed cornice was reported on Saturday. Small loose wet avalanches were reported on Friday. 

The field team reported two slab avalanches that had been triggered by cornices earlier in the week. Check out the MIN here. 

Snowpack Summary

40-60 cm of well settled and bonded snow sits on top of the mid-February crust. Though this layer has not produced avalanche activity, professionals in the area are still treating it with suspicion. The upper snowpack became moist below 1500 m with the recent warm temperatures and will now likely have a crust. Cornices are looming in alpine areas. 

The lower snowpack is well bridged by the mid-February crust and triggering avalanches below this layer is unlikely at this time. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid exposure to slopes that have cornices overhead.
  • Cornice failure may trigger large avalanches.
  • Remember that the snowpack will be significantly different at higher elevations than lower down.

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