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Archived

Avalanche Forecast

Dec 27th, 2019–Dec 28th, 2019
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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.

Though natural avalanche activity has tapered off, human triggering remains likely. Choose less committing terrain and avoid large overhead hazard.

There have been a few close calls already this week.

Weather Forecast

Slightly warmer temperatures for the weekend with a slight inversion on Saturday morning. Expect an alpine high of -8  for Saturday and -4 for Sunday with moderate winds from the West. Skies will remain cloudy with no significant snow accumulations in the forecast.

Snowpack Summary

Surface hoar growth up to 5mm observed below tree line. Moderate SW winds are redistributing the 30-60cm of recent storm snow and forming wind slab on lee aspects. Below the new snow the snowpack structure is generally weak, consisting of facets and depth hoar and a Nov crust up to 2500m.

Avalanche Summary

A couple of windslab avalanches in the past 24 hours on alpine Northerly aspects.  On Wednesday, explosive avalanche control at Sunshine ski area produced a sz 2 deep persistent slab. Recent reports of skier triggered avalanches within the region and reports of whumphing on the deep persistent layer continue today.

Confidence

Avalanche Problems

Deep Persistent Slabs

The weak, faceted lower snowpack remains stressed by the new storm snow at all elevations. If triggered the deep facets it will result in a very large avalanche. Reports of whumphing on the basal layer continue.

  • Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3.5

Wind Slabs

With 30-60cm of storm snow available for transport accompanied by the moderate to strong SW winds, expect fresh wind slab formation in the alpine and exposed areas at tree line.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
  • Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2