Avalanche Forecast

Issued: Dec 21st, 2016 4:00PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Control work today confirm touchy windslabs remain in the alpine and treeline - this layer will need some time to settle and bond with the underlying facets.

Summary

Weather Forecast

Relatively warm winter temperatures, a little more snow and continued westerly winds are forecast for the area. This should be good news in the long term, but it is expected that the new snow or windslab/facet interface will take a while to bond.

Snowpack Summary

The storm has brought us 15 to 30 cm of new snow, with more falling on the West side of the Divide. Moderate to strong winds have created a windslab that overlays a very loose faceted snowpack. The windslab/facet interface was touchy in avalanche control work on Tuesday. The Nov crust is 30-80cm deep, and is not currently reactive.

Avalanche Summary

Size 2 to 3 slab avalanches observed today running far for their mass. The most impressive results on Mt. Bosworth with long propagations & one slope failed when the explosive bag hit the slope. The failure layer are the windslabs on the facets. Not many naturals reported or seen, except for a size 2 over Pilsner climb area on Mt Dennis.

Confidence

Problems

Wind Slabs

New snow and strong winds have created a windslab on exposed slopes in the alpine and tree line that could be easilly skier triggered. This new slab sits over a very faceted snowpack creating a weak interface.

Use caution in lee areas. Recent wind loading have created wind slabs.Be careful with wind loaded pockets while approaching and climbing ice routes.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Dec 22nd, 2016 4:00PM