Avalanche forecast

Banff Yoho Kootenay

Feb 4 – 5, 2018Parks Canada
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Archived · expired 9 years ago

Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanche control on highway 93N Sunday, avoid travel on Hector, Andromache, Dolomite, Helen Lake trail, Observation, Silverhorn, Noyes and Waterfowl Lake Gullies. Dangerous avalanche conditions persist in the forecast region.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3.5
    Three weak layers exist in the upper snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on the aspect and elevation. Destructive avalanches have occurred on these and will continue over the few days.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    15-25cm of new snow has developed a reactive storm slab at higher elevations, If triggered this layer has the potential to step down to deeper instabilities. Stick to non-avalanche terrain until things have a chance to settle

Weather Forecast

Valley bottom temperatures will drop Saturday night with a slight inversion forecast for Sunday, alpine temps expected around -12 to -17. A brief break in precipitation Sunday will bring clears skies before another small system moves in Monday. Winds are expected to remain in the light to moderate range through Sunday.

Snowpack Summary

15-25cm of new snow and moderate winds have developed new storm slabs in the upper snowpack. The main concern in the snowpack continues to be the three persistent weak layers of surface hoar and/or facets that are found between 50 and 100cm down. We continue to observe sudden test results, whumphing and large propagations on these layers.

Avalanche Summary

Natural activity reported Saturday on Bourgeau Left, limited observations due to visibility but the powder cloud reached the Sunshine parking lot (suspect a size 3). Big avalanches with explosives over the last few days show that snowpack remains prime for triggering. Some avalanches ran full path and put dust or debris on roads.

Confidence

Regions covered