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Archived

Avalanche Forecast

Dec 25th, 2014–Dec 26th, 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
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

Regions: Glacier.

A touchy layer should have you tip-toeing around in the mountains. Be conservative in your terrain choices and diligent in group management; regroup is safe spots and be aware of who is above and below you.

Weather Forecast

The forecast is unsettled through Saturday. Mainly cloudy, with light flurries and moderate SW winds at ridgetop. While there won't be enough new snow to add significant load, there is lots of storm snow to be transported by the winds, and windslab development is expected.

Snowpack Summary

Cooling temps will tighten the 50-70cm deep storm slab, which sits on well preserved and widespread Dec 17th surface hoar layer (10-20mm). The surface hoar sits on top of a rain crust up to 2100m, and on well settled snow above 2100m. The Dec 9th surface hoar layer is down 80cm in the area. The Nov 9th crust is 30cm up from the ground.

Avalanche Summary

Avalanche control yesterday triggered 16 size 3 to 3.5 avalanches, including this one off the West face of Cougar Mountain, and over 20 size 2's. Wide propagations were observed. Recently skier triggered and skier remote triggering of the slab from over 50m away continue to occur. Most of the activity was occurring between 1700-2400m.

Confidence

Avalanche Problems

Storm Slabs

A very touchy surface hoar layer is buried by a 50 to 70cm thick storm slab. This layer is widespread, and is likely to be triggered anywhere is has not yet failed. It is easily triggered by light loads (ie you), from distances of up to 100m away.
Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.Avoid paths that have not avalanched recently.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 3

Deep Persistent Slabs

Storm slab avalanches may step down to deeper layers, including the the Nov 9 layer at the bottom of the snowpack. The resulting avalanche would be very large. Some avalanches triggered by artillery control yesterday stepped down to deeper layers.
Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 4