Avalanche Forecast

Issued: Jan 3rd, 2017 4:45PM

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

brian webster, Parks Canada

Banff Yoho Kootenay.

Lake Louise area has had more wind effect and more recent avalanche activity. Alpine hazard is rated CONSIDERABLE in this area.

Summary

Weather Forecast

A mix of sun and cloud for Wednesday. Temperatures will moderate somewhat with day time highs in the alpine reaching -14. Winds will be light to moderate from the north. Thursday may bring some isolated flurries along the divide.

Snowpack Summary

20-30 cm of last weeks storm snow sits over top of a very weak (Dec 19 layer) facet layer which in turn sits on the Nov 12 crust. Winds over the past week have created wind slabs in exposed areas. In many places these wind slabs sit on a weak snowpack comprised of facets and depth hoar.

Avalanche Summary

No new natural avalanches reported today, however a field trip in the Lake Louise area showed numerous avalanches up to size 2.5 from the past four days. These mostly initiated as windslabs and then stepped down into the weak facet layer below. Of note were four avalanches up to Class 2.5 in the Corral Slide Paths adjacent to Lake Louise Ski Resort

Confidence

Wind effect is extremely variable

Problems

Wind Slabs

Wind slabs up to 40 cm thick exist in the alpine and some treeline locations. Even a small wind slab has the potential to step down into the weak facetted mid-pack resulting in a bigger avalanche.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets while approaching and climbing ice routes.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

The mid and lower pack is weak and facetted, and will remain this way for the foreseeable future. This layer is most concerning in areas where a cohesive slab overlies this weak foundation.

Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Jan 4th, 2017 4:00PM