Avalanche Forecast

Issued: Nov 10th, 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.

The limited amount of information available to forecasters points to a reactive crust and facet layer near the base of the snowpack. Use caution particularly as you transition into the alpine.

Summary

Weather Forecast

A weak, fast moving low will pass North to South over the Rockies overnight potentially bringing trace amounts of precip, winds shifting to the North and dropping temperatures into Sunday. Behind this, a ridge will dominate the weather until mid week.

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 in the alpine 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

No new avalanches reported today. There have been several avalanches on the Oct 26 interface over the last week. This includes skier remote triggered avalanches to size 2 along hwy 93N, remote triggered avalanches to size 2.5 resulting from explosives at the Lake Louise ski hill, and several natural events seen 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 and have produced a few skier and remote triggered avalanches. This has been found up to 2800m on shady alpine aspects, with some limited evidence to support its existence on solar aspects.

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

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.

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

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Nov 11th, 2018 4:00PM