Avalanche Forecast

Issued: Jan 23rd, 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.

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

The snow and wind in the forecast may enough to overload one of the several weak layers in some locations, minimize your exposure to overhead hazard. Great skiing can be found in conservative terrain.

Summary

Weather Forecast

A series of small storms are moving in off the coast. Expect light to moderate snow Wednesday (10-15 cm).The most snow will fall to the north and west along the divide with up to 25 cm possible 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.Â In the Sunshine Backcountry in the past 48 hours there have been a couple size 2 natural avalanches. Both were likely cornice triggered out of wind loaded alpine terrain. Also a 0.5 soft slab release on the Jan 16 surface hoar layer on a steeper roll at treeline on a NE aspect.

Confidence

Problems

Wind Slabs

Forecasted wind and snow will form another layer of windslabs in lee features. Pay attention to the surface texture and local wind transport patterns as these will be the biggest indicator of the wind slab problem.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.

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

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Jan 24th, 2018 4:00PM