Archived

Avalanche Forecast

Jan 24th, 2015–Jan 25th, 2015

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

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

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.

Triggering an avalanche is likely, and large natural avalanches are possible over the next couple of days due to warm temperatures, strong West winds and recent new snow. SH

Weather Forecast

A mix of sun and cloud Sunday, with westerly alpine winds reaching 125-150+km/h, and strongest around the Banff region. Temperatures will remain above zero at valley bottom and alpine temperatures will stay just below freezing. We don't expect any significant snow over the next 3 days.

Snowpack Summary

Snowpack tests continue to produce moderate to hard sudden results on the Dec. 18th interface/basal weakness which has become one and the same in most areas with less than 1m of snow. New snow (5-10cm in Banff area, 15cm at Sunshine, 15-20cm in Lake Louise), warming temperatures and strong W winds are creating wind slabs in lee areas.

Avalanche Summary

Numerous natural avalanches were reported today. Notably, the bowl above the Urs hole ice climb on Cascade Mountain had numerous natural avalanches, with one size 3 stepping down to the basal weakness. This was likely triggered by sun. Wind loading in other alpine areas which received more snow saw isolated avalanches to size 2 on lee aspects.

Confidence

Timing or intensity of solar radiation is uncertain on Sunday

Avalanche Problems

Wind Slabs

New wind slabs will be continuing to form in open areas above tree line with the strong W winds, new snow and warm temperatures. These will be prone to human triggering over the next few days.

Be careful with wind loaded pockets while approaching and climbing ice routes.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

In shallower snowpack areas (most of the region) the weak base of the snowpack persists and could be triggered in steep, rocky terrain features. Although in some areas, the Dec. 18th layer persists, management of both layers should be the same.

Be aware of the potential for wide propagations.Avoid thin, rocky or sparsely-treed slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Loose Wet

Strong winds may keep snow surfaces cool at upper elevations, but thin rocky areas on solar aspects should be suspect to warming, and may trigger the weaker basal layers and subsequent larger avalanches.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

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

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2