Avalanche Forecast

Issued: Dec 12th, 2012 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Deep Persistent Slabs.

A.L. Horton, Parks Canada

Jasper.

Conditions are stabilizing but patience is advised before venturing into wind loaded alpine slopes. Stick to sheltered tree line slopes.

Summary

Weather Forecast

Temperatures will remain seasonal (Max -7 Min -15) with no snow in the forecast. Light Westerly winds can be expected at tree line with moderate to strong winds in the alpine.

Snowpack Summary

Wind slab can be found on most lee slopes extending from the Alpine well into tree line elevations. Expect variable wind loading patterns as directions vary with local terrain influences. Cornices are well developed.

Avalanche Summary

An avalanche cycle occurred Sunday into Monday. Slab avalanches to size 3 were observed on NE aspects at alpine and tree line elevations and in some locations, have stepped down to the basal facet layer. Large cornice failure has triggered large avalanches on the basal facet layer as well.

Confidence

Due to the number and quality of field observations on Thursday

Problems

Wind Slabs

Wind slab is present on all open lee slopes from the alpine into tree line elevations. Several natural slab avalanches have been observed on this layer.

Avoid freshly wind loaded features.Be careful with wind loaded pockets while approaching and climbing ice routes.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Deep Persistent Slabs

Slab avalanches and large cornice failures have triggered this weakness on SE to NE aspects in the alpine.� Shallow snowpack areas� and along the edges of snow pockets will be likely trigger spots.

Avoid steep slopes below cornices.Be aware of thin areas that may propogate to deeper instabilites.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 13th, 2012 4:00PM