Avalanche Forecast

Issued: Nov 11th, 2018 4:00PM

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

tim haggarty, Parks Canada

Banff Yoho Kootenay.

Reports of skier triggered windslabs and explosive triggered slabs on the October 26 Crust and Facet Deep Persistent layer continue to come in. Skiers and climbers should be taking a conservative approach on their early season trips.

Summary

Weather Forecast

Although a ridge with dominate the weather until at least late Tuesday, it looks like there will be lingering cloud. There is some potential for an alpine temperature inversion however both treeline and alpine temperatures are expected to remain below freezing. Watch for alpine winds to pick up Tuesday.

Snowpack Summary

In the alpine, 20-50cm with variable wind effect sits on the Oct.26th temperature crust which can be found mainly on shaded aspects treeline and above and is a few cm thick above weak facets. Total snowpack depths are 60-120cm+ in the alpine, tapering dramatically at treeline to below threshold values for avalanche below treeline.

Avalanche Summary

Explosive control work at Sunshine Village produced a sz slab on the October 26 crust in the Delirium Dive and the snow safety team at Lake Louise were working to clean up lingering windslabs. Over the last there have been several instances of natural and remotely triggered avalanches on the October 26 crust through the region.

Confidence

Due to the number of field observations

Problems

Deep Persistent Slabs

The Oct.26 crust and facets react to traffic with whumpfing. This layer has produced a few remote triggered and natural avalanches. While the crust is found at treeline, all avalanches have been reported in the alpine so far.

If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.Remote triggering is a concern, watch out for adjacent slopes.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2.5

Wind Slabs

Recent winds created isolated wind slabs in lees of alpine features. While these have proven reactive in the last couple of days, this problem should diminish as the weather stabilizes and the snowpack settles into next week.

Use caution in lee areas. Recent wind loading has created wind slabs.Be careful with wind loaded pockets while approaching and climbing ice routes.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Nov 12th, 2018 4:00PM