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Avalanche Forecast

Dec 20th, 2012–Dec 21st, 2012
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
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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 Columbia.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Friday: Ridgetop winds back off to mod/strong southerlies. Treeline temp -8. Occasional Flurries. Freezing Level at valley bottom.Friday Night: 10 - 20 cm overnight.Saturday: Southerly ridgetop winds initially light becoming strong late in the day.  Treeline temp -5. Light snow.  Freezing Level at valley bottom.Sunday: Light SW winds at ridgetop.  Treeline temp -5. Lingering flurries. Freezing Level at valley bottom.

Avalanche Summary

Monday's moderate southerly winds drove soft slab formation near ridgetop. Several small wind slab avalanches were reported.  There are still a few reports of fast moving loose snow avalanches coming in too.

Snowpack Summary

More than 120 cm of snow has accumulated this week in some areas. Various storm snow instabilities have been observed. Southerly winds picked up a bit Wednesday evening and created new wind slabs and touchy cornices near ridgetop. The raucous sluffing is likely a thing of the past but still something to keep in mind below treeline, especailly near terrain traps. The mid-pack is reported to be settling well. The late November surface hoar, down 100-160 cm (between 1500 and 2000 m), is producing moderate to no results in snowpack tests, with isolated sudden results. The early November crust, near the base of the snowpack, has produced occasional sudden results in snowpack tests. Professionals are still cautious about these lingering persistent slab problems, but the likelihood of triggering is low. Be wary of steep complex terrain with a shallow snowpack, where triggering a persistent weakness is more likely.

Avalanche Problems

Wind Slabs

Fresh sensitive wind slabs continue to build immediately below ridge crest and in the lee of mid slope terrain features like ribs.  Back off and head to wind sheltered terrain if the snow starts to feel stiff beneath your skis or machine.
Use ridges or ribs to avoid pockets of wind loaded snow.>Recently wind loaded slopes are going to need a few days to stabilize.>The best riding will be found on wind sheltered slopes below treeline.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5