Avalanche Forecast

Issued: Jan 8th, 2012 9:31AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Wind Slabs, Persistent Slabs and Cornices.

triley, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

20-30 cm is forecast for Sunday and overnight into Monday morning combined with moderate to strong southwest winds and freezing levels around 1200 metres. Another 5-10 cm is forecast for Monday with moderate southwest winds and freezing levels dropping to valley bottoms by evening. Cooler and drier weather with light northwest winds is expected for Tuesday and Wednesday.

Avalanche Summary

No new avalanche activity reported.

Snowpack Summary

Strong southwest winds and moderate to heavy precipitation has begun to build new windslabs in the alpine and at treeline. The recent snowfalls add up to about 60-80 cm of "storm" snow that has been available for wind transport. The warm temperatures and high freezing levels caused the wind transported snow to become a well consolidated slab. There are two rain crusts below 1550 metres. The rain crusts are variable, but they are giving planar results in tests. At treeline the storm snow is reported to be giving sudden planar results down 40 cm, and the surface hoar/crust layer that is down 80cm is also giving sudden planar results. This tells me that the new load of snow that we are expecting may activate these weak layers. The mid-pack is reported to be strong, and I have not heard anyone talk about early season layers deep in the snowpack.

Problems

Wind Slabs

New snow and southwest winds are expected to create windslabs in the alpine and at treeline.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Persistent Slabs

Reports of activity on this layer have decreased. Large triggers like explosives and cornice fall have continued to release avalanches that fail down to this weakness. Steep open slopes near treeline may be the most suspect for human triggering.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 7

Cornices

Warm temperatures and strong winds have caused rapid cornice growth which may not be well supported. Try to reduce your exposure beneath these large unstable masses of heavy snow.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Likely

Expected Size

3 - 5

Valid until: Jan 9th, 2012 8:00AM