Avalanche Forecast

Issued: Jan 22nd, 2018 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.

Ian Jackson, Parks Canada

Banff Yoho Kootenay.

The snowpack is complex this year with multiple weak layers. The best way to manage this is to stick to conservative terrain and minimize your overhead hazard.

Summary

Weather Forecast

A series of small storms are moving in off the coast. Expect light to moderate snow with 5- 10 cm per day over the next three days. The most snow will fall to the north and west along the divide with up to 25 cm by end of Thursday. Temperatures will be cool with -10 to -12'C at upper elevations. 3000m winds will generally be moderate to strong SW

Snowpack Summary

Windslabs exist in the alpine. In sheltered areas, 20-30cm of new snow overlies the Jan 16 (the first of 3 weak layers). Below this are the Jan 6 (down 40-50) and Dec 15 (down 60-80). Each of these layers is a mix of sun crust, surface hoar and facets depending on aspect and elevation. Below treeline, the snowpack is facetted with little structure.

Avalanche Summary

No new avalanches were reported or observed today. Yesterday, a couple size 2 natural avalanches were observed in the Sunshine Backcountry. Both were likely cornice triggered out of wind loaded alpine terrain.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

Recent winds and snow have formed wind slabs in immediate lee areas and caused sluffing in steep rocky terrain. Pay attention to the surface texture and local wind transport patterns as these will be the biggest indicator of the wind slab problem.

Use caution in lee areas. Recent wind loading have created wind slabs.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.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

There are 3 weak layers in the upper snowpack: Jan 16, Jan 6, and Dec. 15. All are a mix of sun crust, surface hoar and facets depending on your aspect and elevation. Whumphing is occurring on these layers daily and step down avalanches are possible

Use conservative route selection, choose supported terrain with low consequence.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Jan 23rd, 2018 4:00PM