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Archived

Avalanche Forecast

Dec 27th, 2014–Dec 28th, 2014
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Check out the Tricky Holiday Conditions blog post for more details on the current avalanche scenario.

Confidence

Good

Weather Forecast

A moist low pressure system will linger on Sunday bringing mostly patchy light snowfall, moderate northerly winds and freezing levels at valley bottom. By Monday a dry arctic ridge will set-up for the rest of the forecast period. With this ridge, we'll see mainly clear skies, light to moderate northeast winds and alpine temperatures around -20.

Avalanche Summary

On Thursday a party of skiers triggered a size 2 avalanche on a SW facing slope around 1800m in the Nelson area. Two people were reportedly caught and carried but thankfully ended up on the surface as everything came to a stop. In the north of the region on the same day, a size 2.5 natural slab avalanche failed at 2100m on a north aspect. The mid-December persistent weak layer was the likely failure plane in these events. This type of activity is likely to persist for the foreseeable future.

Snowpack Summary

Light to locally moderate amounts of low density snow have fallen and may have been shifted into wind slabs in high elevation terrain. This new snow overlies recently formed surface hoar.30 - 70 cm of snow from the last week is consolidating into a slab above a touchy weak layer formed in mid-December consisting of surface hoar sitting on a thick rain crust. This combo is thought to extend as high as 2400 m. This persistent layer will likely remain sensitive to human triggering for the foreseeable future. High elevation north facing slopes likely do not have the rain crust, but are still reported to have touchy buried surface hoar. On these slopes, deeper facets or buried surface hoar from earlier in the month may also be lurking. At the base of the snowpack, a crust/facet combo appears to have gone dormant for the time being.

Avalanche Problems

Persistent Slabs

This persistent weak layer, buried up to 70cm below the surface, was responsible for a few close calls over the past week. Conservative terrain selection remains critical.
Use conservative route selection, stick to moderate angled terrain with low consequence and be aware of what is above you at all times as remote triggering is a concern.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 5

Wind Slabs

Light to moderate amounts of new snow are expected on Saturday. Moderate winds may shift these accumulations into new wind slabs on exposed lee slopes. Watch for loose dry avalanches in steep, sheltered terrain.
Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3