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Archived

Avalanche Forecast

Jan 5th, 2021–Jan 6th, 2021
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
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 Yoho Kootenay.

Look for wind sheltered terrain to enjoy the recent snow, and avoid steep wind loaded areas until the newly formed winds slabs have a chance to bond with the layers below. Be mindful of the recent storm snow interface - we saw action on it today!

Weather Forecast

A few cm's of new snow are forecast for Tuesday through Wednesday. Alpine winds will remain in the moderate to strong range out of the W and SW, increasing to strong Tuesday night before dropping to moderate again on Wednesday. Treeline temperatures will be in the -8 to -10 range on Tuesday.

Snowpack Summary

15-40 cm of storm snow at treeline. Wind effect in open areas at treeline and in the alpine. The Dec 13 and Dec 7 sun crust/surface hoar/facet layers are down ~ 50 cm and ~80 cm respectively, sudden planar results in LIttle Yoho today and one explosive triggered size 2 in Sunshine area.  The Nov crust/facet layer sits at the bottom of the snowpack.

Avalanche Summary

Explosive controlled wind slab avalanches to size 2 were reported by the local ski hills.  A few size 1.5  storm slabs were triggered in the Mt. Field area (1950 m) in steep terrain.  One skier remote size 2 avalanche on a steep convex roll below Wawa Ridge near Sunshine was reported on Sunday.  Both avalanche reports failed on a stellar layer.

Confidence

Avalanche Problems

Wind Slabs

Strong winds and recent snow have formed wind slabs in lee areas at treeline and in the alpine. The likelihood of triggering these is slowly going down, but it is a good idea to avoid travel on or under steep loaded terrain for the next couple days.

  • Watch for signs of slab formation, such as whumpfing and shooting cracks.
  • Use caution in lee areas in the alpine and treeline. Recent storm snow has formed wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Storm Slabs

Skier triggered avalanches sizes 1-2 on a layer of stellars at the storm snow interface in the Sunshine & Little Yoho areas. Both were in steep features or on convex rolls.  The snow above is now cohesive enough that we are seeing slab propagation.

  • Convex features and steep unsupported slopes will be most prone to triggering.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible

Expected Size: 1 - 2