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Archived

Avalanche Forecast

Dec 3rd, 2022–Dec 4th, 2022
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.

Users should be cautious around steeper terrain with significant wind effect. There are fresh wind slabs and facet/crust layers near the base of the snowpack that have produced numerous avalanches over the past few days.

Confidence

Moderate

Avalanche Summary

A flight in the Lake Louise group saw a few smaller wind or persistent slabs failing within the last 24 hours. One size 2 on Mt. St. Piran appeared to initiate as a wind slab then step down to the persistent facets at the base. There was a natural size 1.5 observed above Bourgeau Left ice climb which didn't go over the climb. Lake Louise went on a heli bombing mission and got a bunch of size 2's and smaller. They were a mix of new wind slabs and persistent slabs going to ground on the facets.

Snowpack Summary

Wind effect and wind slab development due to variable winds. 20-40 cm of recent snow sits over a very weak layer of facets, surface hoar, or sun crust on steep south aspects. 40-80 cm of total snow exists at treeline throughout the region, with up to 120 cm in loaded alpine features.

Weather Summary

Mostly clear skies Saturday night with ridgetop temperatures in the -15C to -20C range and moderate NW winds. Sunday will see winds shift to the E/NE with trace amounts of snow along the Eastern slopes. Winds will be 30-40kmh in the AM, weakening to 10-20kmh in the afternoon. Alpine temperatures will warm up to -5C to -10C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • If triggered, loose dry avalanches may step down to deeper layers resulting in large avalanches.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.

Avalanche Problems

Wind Slabs

Variable winds have created wind slabs 15-30cm deep on a variety of aspects. They may be triggered on their own, but have been prone to stepping down to the persistent layer of facets near the ground,

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 1.5

Persistent Slabs

Recent snow and wind loading have created slabs over a persistent weak layer of basal facets, buried sun crusts, or isolated pockets of surface hoar. This layer will be around for some time to come.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2.5