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Archived

Avalanche Forecast

Dec 3rd, 2012–Dec 4th, 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
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
3: Considerable
The avalanche danger rating at treeline will be considerable
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: Purcells.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Overnight and Tuesday: Light to locally moderate snowfall / Extreme southwest winds / Freezing level at 1500mWedesday: Light snowfall / Strong to extreme southwest winds / Freezing level at surfaceThursday: Trace amounts of snow / Light southwest winds / Freezing level at surface

Avalanche Summary

No new avalanches to report. This may speak more to a lack of observations than actual conditions. Any field observations can be sent to [email protected].

Snowpack Summary

Over the last few days snowfall amounts have been highly variable throughout the region and windslabs may exist at higher elevations. Reports indicate that up to 50cm of recent storm snow may now sit above a surface hoar layer that developed last week and was buried on the 28th. Although not necessarily widespread in the region, releases on this layer are likely if you have it in your area. There is a surface hoar layer that developed during mid-november was reported to be active last week, but has not been reactive during the recent storm. There is a rain crust near the ground that we're calling the early November crust. There are some facets below it, or it may appear as a sandwich of crusts and facets, but it's been reported  as unreactive at this time. There is still a sharp transition in snow depth from treeline to below treeline making back-country travel challenging under 1300 m in elevation. In general, significant variations in snowpack structure exist across the region. Digging down and making your own observations will be critical to safe slope selection. Any observations from the field are welcome at [email protected].

Avalanche Problems

Storm Slabs

Forecast snowfall and extreme winds will create new wind slabs and potentially add to the reactivity of a storm slab that has been developing over the past few days. With expected wind values, loading may take place lower on the slope than normal.
Be alert to conditions that change with elevation.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

Two problem layers exist: A surface hoar layer 30 - 60 cm below the snow surface and the early Nov. crust near the ground. It may be possible for a rider to trigger these weak layers, especially in areas where the snowpack is thin and/or rocky.
Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5