Avalanche Forecast

Issued: Dec 18th, 2016 4:27PM

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

Conrad Janzen, Parks Canada

Banff Yoho Kootenay.

The hazard continues to increase with the strong winds and some new snow on the way. More conservative terrain choices will be the best bet for the next day or two until the snowpack has a chance to stabilize.

Summary

Weather Forecast

Warmer temperatures and 5-10cm of new snow are forecasted to arrive on Sunday night and into Monday. This approaching system is expected to arrive with moderate to strong West winds at higher elevations.

Snowpack Summary

Moderate to strong winds creating widespread wind slabs above tree line. In sheltered areas the top 30cm of the snow pack is loose facets, and most areas with a snowpack of less than 60cm consist entirely of loose unconsolidated facets. The Nov 12 layer is down 30-80cm and not currently reactive though test results on this layer are variable.

Avalanche Summary

Several natural and skier triggered wind slab avalanches up to size 1.5 were observed and reported on Sunday. Loose snow avalanches up to size 1.5 are occurring in steep terrain with the strong winds. Some of these avalanches are traveling further than expected because of the weak faceted snowpack acting as marbles near the ground.

Confidence

Forecast snowfall amounts are uncertain on Monday

Problems

Loose Dry

The surface snow is facetted and weak allowing for wind triggered large sluffs in steep terrain. These sluffs are picking up mass and running far. Pay attention to terrain traps where snow can accumulate into deeper deposits.

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

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

Strong winds have added to the wind slab problem. By now the alpine snowpack is highly variable ranging from impenetrable hard slab to loose faceted snow. Probe often to determine the extent of the wind slabs and avoid them in steep terrain.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 19th, 2016 4:00PM