Avalanche Forecast

Issued: Jan 21st, 2015 4:00PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

The snowpack is slowly strengthening; however, conservative decision making in bigger alpine terrain is still essential! We may see some snow late friday PM which would cause the danger to rise again.

Summary

Weather Forecast

Thursday and Friday look to be similar to the last few days - mild temperatures, light winds and scattered clouds. Friday afternoon, we should see increased winds from the West and 10-15 cm's overnight with freezing levels rising to ~1500m.

Snowpack Summary

The snowpack remains fundamentally weak, with a combination of windslab, surface hoar and basal facets all causing concern in different types of terrain. Snowpack tests continue to produce moderate to hard sudden results on the basal weakness/ Dec. 18th interface which has become one and the same in many areas.

Avalanche Summary

No natural avalanches observed, but forecasters on Mt. Field reported a couple large whumphs in an open area below treeline, indicating human triggering of deeper weak layers is still possible in the right terrain.

Confidence

Forecast snowfall amounts are uncertain on Saturday

Problems

Wind Slabs

Surface windslabs formed on Jan 18/19 can be triggered by skiers and climbers. Feel for tension in the surface snow and avoid freshly windloaded terrain.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

In shallower snowpack areas (most of the region) the weak base of the snowpack persists and could be triggered in steep, rocky terrain features. Although in some areas, the Dec. 18th layer persists, management of both layers should be the same.

Avoid thin, rocky or sparsely-treed slopes.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 22nd, 2015 4:00PM