Avalanche Forecast

Issued: Jan 16th, 2018 4:22PM

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

grant statham, Parks Canada

Banff Yoho Kootenay.

Two days of avalanche control has produced mixed results. Most areas in Banff, Yoho and Kootenay produced only a few avalanches to size 2. However, down in Little Yoho we triggered several large size 3s that blew over the climbs and covered the road.

Summary

Weather Forecast

The ridge of high pressure is breaking down and a Pacific storm will cross the region starting Wednesday afternoon. Wednesday itself will be colder (-4 to -10) with winds picking up from the west and snow starting in the afternoon. Expect up to 15 cm by the end of the storm on Thursday afternoon.

Snowpack Summary

Recent warm temperatures aloft have settled the upper snowpack and formed suncrust on S and W aspects. 30-50cm of snow sits over the Dec.15 persistent weak layer of facets and surface hoar. The overlying slab propagation is extremely variable across the region with stability of the snow being specific to each slope.

Avalanche Summary

Two days of avalanche control has produced smaller results than expected in all areas except near Field. Bourgeau, Whymper, Simpson and Bosworth each produced a few avalanches up to size 2 failing on the Dec 15 facet layers, but the results were not as widespread as anticipated. Mt. Dennis ice climbs in Field produced large avalanches up to size 3.

Confidence

Problems

Persistent Slabs

This layer continues to be the cause of much uncertainty with forecasters - we think its bad, but yet it has not yet produced many large avalanches. We remain uneasy about it despite indications of generally good conditions.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Jan 17th, 2018 4:00PM