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Archived

Avalanche Forecast

Dec 22nd, 2011–Dec 23rd, 2011
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
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
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: Northwest Inland.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Friday: Snow amounts up to 5cms. Ridgetop winds 40km/hr from the SW. Treeline temperatures near -5. Saturday: Snow amounts up to 10cms. Ridgetop winds 80km/hr. Freezing levels hover around 1000m. Sunday: Snow amounts 10-20cm. Freezing levels 1200m in the morning falling back to valley bottom Sunday night.

Avalanche Summary

No new avalanche activity has been reported. Any information (professional or recreational) from the field is highly appreciated. Please send your observations to [email protected].

Snowpack Summary

Early in the week the region received up to 20cms of new snow accompanied by strong southwest winds. Storm snow and wind slabs are forming. There is now around 50cms of snow sitting on a weak interface. This weakness is the December 12th surface hoar/crust/facet combo. What is the tipping point of this weak interface? In areas where this interface has reached its threshold avalanches have occurred. If they have yet to happen naturally, I suspect they are very touchy and will react to a rider trigger. Observations suggest there is faceting above and below the buried crust. The crust being a result from rising freezing levels, then the early December dry spell. This crust is widespread and is lingering in most start zones up to 2000m. In short, the upper snowpack is variable and showing easy shears in test results. The avalanche problems exist in the upper meter of the snowpack on this weak interface. Beneath this the midpack is well settled and strong.

Avalanche Problems

Persistent Slabs

Reactive storm slabs have now formed at all elevations. Especially where the mid December buried surface hoar/crust/facet layers exist.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Wind Slabs

Wind slabs have developed on lee and cross-loaded terrain in the alpine and at treeline. Rider triggered wind slabs are likely.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3