Avalanche forecast

Banff Yoho Kootenay

Dec 5 – 6, 2013Parks Canada
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Avalanche danger

Thu
Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

10-20 cm was received in the forecast area earlier in the week, with the greatest amounts in the Eastern part of the region. Cold temperatures will remain and expect a gradual weakening of the snowpack support.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Reverse loading has created new slabs on southerly aspects. Although less reactive with the colder temperatures, watch out for lingering wind slabs on N-NE aspects.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    The October melt freeze crust and basal depth hoar are a a concern and avalanches may step down to basal layers. This is primarily a concern on steeper features especially if they are windloaded.

Weather Forecast

The alpine temperatures will dip to -30 by Friday, but become slightly warmer by the weekend to -20C for a high. Winds will remain light from the North. The Arctic high pressure will be in the region for the next several days.

Snowpack Summary

10-15 cm fell with moderate- strong North winds as the Arctic air moved in 2 days ago. Some reverse loading of slopes may have created some new windslabs in the alpine. There is 65-85 cm at our treeline study plots and some mid-pack support for skiing. Field tests still show failures on the Oct 27 crust where it exists or on the basal facets.

Avalanche Summary

In the last 24 hours, a size 2 avalanche occurred on a NW aspect of Copper Mountain, just west of Banff, at about 2350 m. It started as a point release which then triggered a 80 m wide slab that failed near ground, down 100-150 cm.

Confidence

Regions covered