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Avalanche Forecast

Dec 21st, 2012–Dec 22nd, 2012
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
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
1: Low
The avalanche danger rating below treeline will be low

Regions: South Columbia.

Confidence

Good

Weather Forecast

Saturday: Strong SW ridge top winds diminishing after sunset. Light snowfall. 1500m temp: -3 Freezing level: SurfaceSunday: Moderate SW ridge top winds. 1500m temp -6. Occasional flurries. Freezing Level: SurfaceMonday: Light SE ridgetop winds. Treeline temp -8. No snow. Freezing Level: Surface

Avalanche Summary

We're starting to see the effect of the big winds midweek.  Near treeline, slab avalanches to size 2 were triggered by both vehicles and skiers.  A few bigger features in the alpine released large natural avalanches to size 3 on N through E facing slopes.  Out of the wind, there's still some sluffing in the new snow 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/Thursday 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, especially 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

Wind slabs should slowly diminish in sensitivity this weekend, but I suspect they're still capable of failing and taking you for a ride. Watch for wind slabs immediately below ridge crest and in the lee of mid slope terrain features like ribs.
Use ridges or ribs to avoid pockets of wind loaded snow.>Use all your senses to avoid wind affected slopes. If you see obvious signs of wind loading, or you feel the snow stiffen under your skis or machine, back off and head to wind sheltered terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5