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Archived

Avalanche Forecast

Dec 9th, 2021–Dec 10th, 2021
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
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
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.

Winds will increase later on Friday as a storm makes its way into the Rockies for Saturday. Watch for slowly increasing hazard due to wind transported snow later in the day.

Weather Forecast

A NW flow will keep the temperatures cool on Friday with a warming trend and more snow expected on Saturday. Temperatures at treeline on Friday in the -10 to -15 C range and moderate winds from the NW. Some flurries expected overnight Thursday and into Friday. Saturday looks like a potentially big snowfall.

Snowpack Summary

5-20 cm of new snow over the last 36 hrs makes for 15-30 cm of soft surface snow above the Dec 2 rain crust. This crust disappears between 2100-2250 m. At treeline and above, moderate winds are developing soft slabs in immediate leeward slopes. The weak Nov 5 crust/facet interface is present near the ground.

Avalanche Summary

Ski cutting and explosive work at the local ski areas produced wind slabs from size 1-.5 on Thursday. No new natural avalanches were reported or observed but visibility was limited. The last significant skier triggered avalanche was a skier accidental size 3 triggered on Lipalian Mountain (near Lake Louise) on Sunday.

Confidence

Forecast snowfall amounts are uncertain on Saturday

Avalanche Problems

Wind Slabs

Wind slabs have developed in immediate lee areas at treeline and in the alpine. These are possible to skier trigger in some areas so use caution in all steep leeward terrain at treeline and above.

  • Be careful with wind loaded pockets while approaching and climbing ice routes.
  • Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Deep Persistent Slabs

We continue to see occasional high consequence avalanches on the Nov 5 crust/basal facets in specific terrain features. Some slabs have initiated on this layer, while others were "step down" avalanches triggered as wind slabs or cornices hit them.

  • Avoid steep convexities or areas with a thin or variable snowpack.
  • Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3