Avalanche Forecast

Issued: Jan 2nd, 2017 4:00PM

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.

Watch for steep terrain where a cohesive slab sits over the weak facets of the lower snowpack. Human triggering is possible in these areas and we have seen several recent avalanches on these facets. Probe often or dig to find these spots.

Summary

Weather Forecast

The arctic ridge of high pressure has arrived and will dominate for the next few days. Dress warm!! Lows of near -30'C are expected with daytime highs reaching -18'C under clear skies with light winds from the north. It looks like the temperatures will start to moderate and rise slowly by Wednesday.

Snowpack Summary

The snowpack is mostly weak and facetted, with 15-25 cm of recent snow as the surface layer. Winds over the past week have created wind slabs in exposed areas, and in many places these wind slabs sit on a weak snowpack comprised of facets and depth hoar. A snow profile done Sunday in the Helen Shoulder area showed a very poor snowpack structure.

Avalanche Summary

Two size 2-2.5 natural avalanches in the Corral 1 and 2 paths, and a size 2 natural on Ptarmigan Peak observed Monday outside the Lake Louise ski resort. A recent size 2.5 avalanche was observed on the N side of Mt Burgess as well as a couple smaller slides on the SW aspect of Wapta Peak. All appear to be failing on the weak mid pack facets.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Pay close attention to the texture of the snow surface as you are traveling. Watch out for dense, wind drifted snow which could indicate the presence of a wind slab. Areas near ridge crests or sides of gullies are obvious places to find these.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

The bottom of the snowpack is weak and facetted, and will remain this way for the foreseeable future. In most areas there is not much of a cohesive slab overlying this weak foundation, but it is still advisable to avoid large avalanche start zones.

Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Jan 3rd, 2017 4:00PM