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Avalanche Forecast

Mar 6th, 2013–Mar 7th, 2013
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: South Coast.

Avalanche danger below treeline is LOW in the Cascades where the surface rain crust extends up to higher elevations.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Thursday: Light amounts of new snow (trace amounts in the north) / Light northwest winds / Freezing level at 1300mFriday: Mix of sun and cloud / Light north winds / Freezing level at 1600mSaturday: Clear skies / Light northwest winds / Freezing level at 1900m

Avalanche Summary

Natural avalanche activity decreased on Sunday but there was one report of a size 2 skier triggered avalanche in the Duffey Lake area that resulted in injuries. Explosive control on the Duffey Lake road also produced several avalanches up to size 3 from northwest aspects. Most of these were suspected to have released on the late February surface hoar layer. There were no reports of new avalanches on Monday or Tuesday.

Snowpack Summary

Moderate ridge top winds have formed new wind slabs in exposed lee terrain. A dusting of new snow sits on 60-100 cm of settling storm snow or a rain crust below 1400 m in the north and 1700 m in the south. A weak layer of buried surface hoar (February 20th) and/or a crust sits at the base of the storm snow. This layer was the culprit in most of the large avalanches that occurred last weekend. Snowpack tests continue to show moderate "pops or drops" results and good potential for propagation. Triggering this layer is becoming more difficult, but I recommend avoiding any large slopes that did not release during the last cycle, especially when the sun pokes out this week.

Avalanche Problems

Persistent Slabs

60-120 cm of settling storm snow sits on a persistent weak layer (surface hoar or crust). Triggering this layer is becoming less likely but extra caution should be given on all slopes over 30 degrees that did not previously slide.
Conditions have improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 7

Wind Slabs

Wind slabs can be found on a variety of aspects and could be triggered by the weight of a person.
Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3