Avalanche Forecast

Issued: Jan 24th, 2015 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs, Deep Persistent Slabs and Loose Wet.

snow safety, Parks Canada

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

Summary

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

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

Valid until: Jan 25th, 2015 4:00PM