Archived

Avalanche Forecast

Nov 22nd, 2017–Nov 23rd, 2017

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Banff Yoho Kootenay.

The first major avalanche cycle of the season will peak on Thurs. Avoid all avalanche terrain. There is a significant weak layer deep in the snowpack that is active and we expect widespread avalanche activity.

Weather Forecast

A strong south-westerly flow dominates the region bringing rain, snow and warm temperatures. Rain is expected to reach 2200m Thursday morning followed by snow as the moist air lifts over the colder incoming air. Thursday evening should be winter again with colder temps and snow..

Snowpack Summary

The snowpack near treeline has a variable depth between 60cm and 1m. The main feature of concern is a facet layer associated with the halloween raincrust. This layer has been causing avalanches, extensive whumphing, and has had good propagations.

Avalanche Summary

Visibility was generally poor throughout the forecast area but some slab avalanches to size 2.0 were noted throughout.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Persistent Slabs

This is an active avalanche problem and is the main reason people should avoid all avalanche terrain Thursday. The problem exists in most terrain and will become overloaded with the incoming storm. Watch overhead hazard.

Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Winds up to 100 km/hr are forecast for Thurs which will load the new snow onto leeward aspects. Windslabs should be expected near all ridges and gully areas and can be expected to become large once triggered.

Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Loose Wet

Warming temperatures and rainfall will create wet avalanches in gully areas below treeline. Ice climbers in particular should avoid gully climbs for the next 48-hours.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 2