Archived

Avalanche Forecast

Dec 26th, 2024–Dec 27th, 2024

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, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.

The primary concern is that superficial slabs could step down to the deep, persistent weakness, resulting in full-depth avalanches. However, we are uncertain about how reactive these layers are, as we have received limited observations over the past few days.

Confidence

Low

Avalanche Summary

No new avalanches were observed or reported on Thursday.

Snowpack Summary

15-20 cm of storm snow from the past week, combined with strong W/SW winds, has formed wind slabs in alpine lee areas which extend down into treeline.

The mid and lower snowpack is faceted and weak, with facet/crust interfaces near the ground. This is more pronounced east of the divide, while western regions display a deeper more settled snowpack.

Snowpack depths at tree-line are about 60 cm in eastern areas and 100 cm west of the divide.

Weather Summary

A mix of sun and cloud, alpine winds West 30-40kmh, and trace amounts of snow. See below for table.

Terrain and Travel Advice

Avoid freshly wind-loaded features, especially near ridge crests, rollovers, and in steep terrain.
Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.

Avalanche Problems

Deep Persistent Slabs

Weak facets and depth hoar associated with crusts near the base of the snowpack have caused recent avalanches 60-100 cm deep. Any area with a stiffer slab over the facetted lower snowpack can generate a larger avalanche that steps down to the ground.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1.5 - 3

Wind Slabs

Moderate to strong S and SW winds have built wind slabs in lee features in the alpine and down into treeline. These slabs are a concern where they sit over weak facets that could "step down" to the basal layers.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 1.5