Avalanche forecast

Banff Yoho Kootenay

Dec 29 – 30, 2019Parks Canada
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Archived · expired 7 years ago

Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate

Highlights

Keep to low angled terrain and avoid exposure to large overhead features. While ski tracks are starting to push out, there is a great deal of uncertainty with the recently overloaded weak layers at the base of the snowpack.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Wind effect is evident in the alpine along the divide with areas such as the Wapta looking hammered . While much of treeline seems to have been spared, it would be wise to expect to find slabs in more exposed areas there too.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5

    The weak, faceted lower snowpack remains stressed by the new storm snow at all elevations. If triggered the deep facets it will result in a very large avalanche. Reports of whumphfing on the basal layer continue as recent as Friday.

Weather Forecast

After a clear, chilly overnight period, warm air entered the region today creating mild inversions. Expect an alpine high of -4 for Sunday, again with the potential for inversions, as cloud cover increases and winds diminish. Cloud cover will increase Monday as winds return and snowfall becomes possible late in the day. 

Snowpack Summary

Moderate to Strong W and SW winds have redistributed snow in the alpine and the upper areas of treeline. Snowpack depths at treeline range from 100 to 160cm. The Nov crust is found ~ 30cm above the ground and is present up to 2500m. The weak facets sitting above this crust are an obvious weakness and are more developed in shallow areas.

Avalanche Summary

Recent reports of skier triggered avalanches within the region and reports of whumphfing on the deep persistent layer have continued in the last 24 hrs. Explosive avalanche control at local ski areas today  produced a few sz 1 to 2 windslabs in steep, wind loaded areas as has been seen over the last few days.

Confidence

Due to the number and quality of field observations

Regions covered