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Archived

Avalanche Forecast

Feb 11th, 2017–Feb 12th, 2017
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
Human triggered avalanches will be likely on Sunday, and the possibility of very large natural avalanches remains possible. Stay on conservative terrain and avoid overhead exposure while the snowpack adjusts to the new load.

Weather Forecast

Continued moderate to strong westerly winds for Sunday, only trace amounts of snow, and temperatures in the -10 range at treeline.  We will see a slow rising of the temperatures over the next 5 days, with valley temperatures well above freezing, and alpine temperatures approaching 0C. 

Snowpack Summary

30-60cm of new snow in the past 10 days with extreme winds from the SW have created new snow slabs over a fundamentally weak snowpack comprised mostly of facets, buried wind layers, and depth hoar. We expect more avalanches on these weak facet layers over the next while as the snowpack adjusts to the load.

Avalanche Summary

Many natural, skier, and explosive triggered avalanches were observed and reported throughout the forecast region up to size 3 in the last 48hrs. Most are occurring within the storm snow, 30-60cm deep, with some "step down" avalanches in the deeper weak layers of the snowpack. These have been on many aspects and all elevations.

Confidence

Avalanche Problems

Wind Slabs

Expect drifted snow to be deeper than 100 cm in leeward areas on Sunday and very susceptible to human triggering over the next few days. Give avalanche terrain a wide berth as fracture lines may extend further that you expect.
Avoid freshly wind loaded features.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The new snow has created a touchy slab over the weak facets at all elevations, resulting in many avalanches that could potentially run full path, of which there have been numerous examples.
Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 4

Loose Dry

Wind loading has resulted in numerous loose dry avalanches over the last 48 hours out of steep cliffs and gullies. This problem will remain Sunday as wind speeds stay elevated.

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

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2