Avalanche Forecast

Issued: Mar 10th, 2017 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Human triggering is going to be a problem this weekend. Avoid exposure to avalanche terrain.

Summary

Weather Forecast

Continued flurries, moderate winds, and moderately cool temperatures are unlikely to do much to reduce the deep instabilities in the area.

Snowpack Summary

50-60cm of storm snow over the past week has been surprisingly reactive. Winds will continue to move the new snow onto lee (east) slopes. The weak faceted base released in many avalanches over the past week as smaller avalanches stepped down, or a tipping point was reached in slab weight.

Avalanche Summary

Large avalanches have been running this week naturally, or with explosives along the highway. Some of the failures have been associated with less steep areas and these slides have been running surprisingly far. It is expected that the natural activity will be reduced but human triggered avalanches will continue to be touchy and likely.

Confidence

Problems

Wind Slabs

50cm of dry snow from the past week is being blown into cohesive windslabs at higher elevations. Expect these to react easily to triggers, and keep your distance from avalanche starting zones. We have seen long propagations up to 400m this past week.

Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The entire snowpack is built upon a structurally weak base, which produces very large avalanches when triggered. There is tremendous uncertainty with this sort of condition, and the only way to hedge against it is to avoid the big avalanche terrain.

Be aware of thin areas that may propogate to deeper instabilites.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 11th, 2017 4:00PM