Avalanche forecast

Banff Yoho Kootenay

Jan 2 – 3, 2014Parks Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

The hazard may go to high Thursday if we get more snow than forecast. Given the sensitive nature of the basal weakness, it will be best to limit your exposure to avalanche terrain until we see what this storm produces. SH

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Watch for areas of wind loading. If a wind slab is triggered it may step down to deeper layers.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    This is mainly a problem at treeline and below, West of the divide where 40-70cm of snow has fallen over the last six days. There has been less wind in these areas, and high humidity has promoted slab development over the facets.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3
    This is the predominant layer in the snowpack, and full depth avalanches to ground have been observed daily over the past week. This will increase in frequency with the new snow.

Weather Forecast

Snowfall amounts have backed off from previous forecasts.  Starting Thursday afternoon, we can still expect 10-20 cm of snow by Friday (lesser amounts in Eastern regions). Winds Thursday will be mod-strong westerlies, with gusts into the extreme range. This may bump the hazard to High in the bulletin region on Thursday and Friday.

Snowpack Summary

W. of the divide there is 40-70 cm of fresh snow over the past 6 days and 10-20 cm on the East. Continued west winds have added to the slab condition in the alpine and at treeline. The treeline snowpack depth is roughly 1 metre deep. The midpack is supportive on skis but is consists mostly of weak facets with a persistent weak layer at the ground.

Avalanche Summary

Avalanches to size 2.5 over the past few days have been reported with mainly the same characteristics, which are wind slabs failing to ground on the basal weaknesses. Two cornice triggered size 2 avalanches were observed on E/SE. facing Healy creek paths. These were new wind slabs which did not step down to ground and were roughly 40-50cm thick.

Confidence

Forecast snowfall amounts are uncertain on Thursday

Regions covered