Avalanche Forecast

Issued: Jan 23rd, 2017 4:09PM

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

brian webster, Parks Canada

Banff Yoho Kootenay.

Summary

Weather Forecast

Tuesday will bring a mix of sun and cloud with day time highs in the alpine around -10. Winds are forecast to be light and freezing levels will be near the surface.

Snowpack Summary

20-30 cm of settled storm snow overrides a generally weak and facetted midpack and base. Closer to the divide and in deeper snowpack areas the midpack is more supportive. Some lingering windslabs exist in the alpine.

Avalanche Summary

Avalanche control in Yoho Park today (Mt Bosworth, Mt Stephen, and Mt Dennis) produced numerous size 2 and 2.5 avalanches. One size 3 avalanche was triggered on Mt Bosworth. These avalanches were either storm slabs or wind slabs that stepped down into a lower facet layer.

Confidence

Problems

Deep Persistent Slabs

The midpack in most areas is weak and facetted. Any slab sitting overtop of this weakness should be considered suspect. There is a high level of uncertainty and variability concerning this layer.

Carefully evaluate terrain features by digging and testing on adjacent, safe slopes. Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Small windslabs persist in lee alpine areas. Watch for these wind slabs as you approach ridge-tops and cross-loaded features.

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

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 24th, 2017 4:00PM