Avalanche Forecast

Issued: Jan 7th, 2017 5:01PM

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.

snow safety, Parks Canada

Banff Yoho Kootenay.

While only occasional natural activity has been observed, open areas still hold the potential for larger releases of slab over the weak facets. The overall structure is poor and any steep terrain should be treated cautiously.

Summary

Weather Forecast

Cool temperatures and light flurries are forecast. As of yet things are still forming but we may be looking at a bit of snow and slightly warmer temps reaching us by Sunday night before things dry out and cool down again by Tuesday. Unfortunately, the snowpack is presently weak and cannot support loading.

Snowpack Summary

Winds over the past week have created wind slabs in most alpine areas. 20-30 cm of facetting recent snow and wind slab sits over top of the weak December facet layer which in turn sits on the Nov 12 rain crust. This poor snow structure of firm snow over weak facets will likely be with us for some time and is not something to put much confidence in.

Avalanche Summary

On a flight from Banff to the Bow Peak area Saturday, a number of recent natural slab avalanches up to size 2 on all aspects above treeline were observed. These slabs failed on the weak mid pack facets and several of them within the last couple days. Two small loose dry avalanches were noted in Kootenay on Friday from steep rocky terrain.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Monday

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.

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

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

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

Expected Size

1 - 3

Valid until: Jan 8th, 2017 4:00PM