Avalanche Forecast

Issued: Jan 4th, 2014 4:32PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Natural avalanche activity is slowing down however the potential for human triggered avalanches remains high. Ski quality has improved significantly especially near the divide but enjoy the new snow by sticking with conservative terrain choices! CJ

Summary

Weather Forecast

Clearing skies for Sunday with Moderate NW winds and temperatures falling to the low -20's overnight.Â Slightly warmer temperatures for Monday with some cloud and gusty W winds at tree line with more seasonal temperatures on Tuesday.Â Little to no precipitation is expected over the forecast period.

Snowpack Summary

20-30cm of recent storm snow with new wind slabs forming near ridge crests and in the alpine. This new snow overlies previous wind slabs which sit over the basal depth hoar/crust. Moderate compression test results found at tree line with sudden collapses on the depth hoar. A supportive mid pack is found near the divide and to the W.

Avalanche Summary

Today a skier accidental size 2 occurred in the W Bowl at Lake Louise which then triggered a size 2.5. Both avalanches failed on the basal facets. Yesterday numerous avalanches to size 2.5 stepping down to ground were observed in the alpine on all aspects including a size 2 on Pilsner Pillar, Mt. Dennis and a size 2 left of Silk Tassel, Mt. Field.

Confidence

Problems

Deep Persistent Slabs

The mid pack is strengthening in thicker snow pack areas but this means the potential for larger propagations on the weak basal layers is a real concern. Stick to moderate angled well supported slopes and minimize exposure to large avalanche paths.

Be aware of thin areas that may propogate to deeper instabilites.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

New wind slabs are forming with lots of new snow available for transport. If triggered these have the potential to step down to deeper facet layers and create large avalanches. Probe for new or old wind slabs and avoid steep lee loaded terrain.

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

Likely

Expected Size

1 - 2

Valid until: Jan 5th, 2014 4:00PM