Avalanche Forecast

Issued: Nov 27th, 2014 4:00PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Touchy windslabs continuing to build. Another 25 cm with gusty SW winds expected before storm ends mid-day Friday. For climbing, it's a good time to stay clear of avalanche terrain and skiers should avoid open windloaded slopes and overhead hazard.

Summary

Weather Forecast

Another 25 cm is forecasted for the region tonight and ending mid-day Friday. Winds will be SW light - moderate SW with gusts to 60 km/hr. On the heels of the snow ending, the temperatures will plummet to -30 for Saturday & Sunday with highs of -20C. Monday temperatures start to warm slightly.

Snowpack Summary

There is approximately 30 cm of storm snow (more at higher elevations closer to the divide). The new snow is not bonding well to the underlying weak faceted midpack that blankets the region. At the base is the early November rain crust, which also poses a step down concern.

Avalanche Summary

Avalanches to size 2 were observed today in lee terrain in the alpine. Avalanches were failing at the storm snow interface and some stepped down to the Nov 6 rain crust (40-50 deep).

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

Windslabs continue to develop with ongoing storm. Slabs are now up to 40 cm thick. Expect the potential for propagation to increase as they become more dense. Watch for slabs in all leeward areas in addition to loose snow avalanches in gullies.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Any wind/storm slab triggered will likely step down to the Nov 6 rain crust or to the ground and entrain the weak faceted snow pack. This would be a nasty ride through boulders and trees.... Avoid all open avalanche terrain during the storm.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 28th, 2014 4:00PM