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Avalanche Forecast

Dec 5th, 2012–Dec 6th, 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
1: Low
The avalanche danger rating below treeline will be low
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
1: Low
The avalanche danger rating below treeline will be low
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
1: Low
The avalanche danger rating below treeline will be low

Regions: South Rockies.

Confidence

Fair - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

Overnight and Thursday: Light snowfall / strong west winds decreasing to moderate and northwest by Thursday / Freezing level at surfaceFriday: Light snowfall / moderate to strong northwest winds / Freezing level at surface  (note: models are in disagreement regarding snowfall amounts for Friday. Amounts may be closer to 15cm)Saturday: Trace amounts of snow / Light west winds / Freezing level at surface

Avalanche Summary

I expect fairly widespread windslab activity in the wake of the strong winds and snowfall on Tuesday night.

Snowpack Summary

Recent storm accumulations have been highly variable throughout the region; however, some ares have seen moderate to heavy snowfall over the past few days. In general winds have been strong creating widespread windslabs at higher elevations. Warmer temperatures and rain at lower elevations have created moist surfaces that will most likely form a temperature crust with dropping freezing levels.At the base of the snowpack you may find the early November crust which is associated with a layer of facets either directly above or below.In general, snowpack data is sparse in this region and significant variations likely exist from one drainage to another. Digging down and making your own observations will be critical to safe slope selection. Any observations from the field are welcome at forecaster@avalanche.ca.

Avalanche Problems

Wind Slabs

Light to locally heavy snowfall and strong winds will have created new wind slabs and potentially add to the size and reactivity of existing storm slabs. With high wind values, loading may take place lower on the slope than normal.
The new snow may require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

We have not heard of any new releases on this early season rain crust; however, an avalanche at this interface could be surprisingly large and destructive. This layer may become reactive with increased loading.
Be alert to conditions that change with elevation.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5