Avalanche Forecast

Issued: Dec 19th, 2016 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 Loose Dry.

William Lawson, Parks Canada

Banff Yoho Kootenay.

Reports of two skier accidental and numerous natural avalanches today to size 2 failing on the developing wind slab facet interface.

Summary

Weather Forecast

More snow is expected to fall with amounts ranging from 5-10cm in the next day. As this system moves through, moderate to strong westerly winds will continue to persist at higher elevations. Temperatures are forecasted to remain between -5 to -15 for the next few days.

Snowpack Summary

Moderate to strong winds have transported 5-15cm of new snow creating a dense wind slab above treeline, This wind slab ranges from 10-50cm thick and overlay a very loose faceted snowpack creating a weak interface that produced easy results in our snowpack tests. The Nov crust is still present ranging from 30-80cm deep and not currently reactive.

Avalanche Summary

Increase avalanche activity today, natural and skier trigger avalanches to size 2 on wind affected slopes. Releases are failing on the wind slab facet interface and possibly entraining loose facets from deeper in the snowpack. Though the wind slab is the primary concern we suspect loose dry avalanches are still prevalent in steep alpine terrain.

Confidence

Problems

Wind Slabs

New snow and strong winds have created a reactive wind slab on exposed slopes in the alpine and tree line. This new slab sits over a very faceted snowpack creating a weak interface. Natural and skier trigger avalanches to size 2 were reported today.

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 - 2

Loose Dry

Combinations of new snow and loose facets are contributing to this problem, expect sluffing out of steep alpine slopes and gullies. These sluffs are picking up mass and running far.

The volume of sluffing could knock you over; choose your climb carefully and belay when exposed.Be aware of party members below you that may be exposed to your sluffs.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 20th, 2016 4:00PM