Avalanche Forecast

Issued: Dec 9th, 2019 4:12PM

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

Parks Canada Conrad Janzen, Parks Canada

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Enjoy the great snow but stick to more conservative terrain, minimize exposure to large slopes and avoid terrain traps for a few days. In many areas there is a significant slab over a weak base and it will take time for the snowpack to improve.

Summary

Weather Forecast

Continued NW alpine winds in the moderate range are expected overnight, increasing to strong on Tuesday. Temperatures should remain seasonal in the -10 range at treeline. Minimal snow, and a mix of sun and cloud for the next couple days.

Snowpack Summary

Moderate winds in the alpine creating small wind slabs. Recent storm snow has formed a slab at treeline and above. Below the storm slab, the snowpack structure is generally weak, consisting of facets and depth hoar. The Nov crust is present up to 2500m and ~30 cm up from ground. Snowpack depths at treeline range from 80-160 cm.

Avalanche Summary

Avalanche control on Sunday and Monday produced numerous size 2 and a couple size 3 avalanches. The largest slides were failing on the Nov crust and basal facets. A skier accidental size 2.5 occurred in West Bowl at Lake Louise Sunday. This avalanche also slid on the Nov crust layer. Natural avalanche activity has slowed, but not stopped.

Confidence

Problems

Storm Slabs

An icon showing Storm Slabs

Recent snow and wind have formed a storm slab in many open areas at treeline and in the alpine. Human triggering of this slab remains possible or even likely in some terrain, though natural avalanche activity has slowed down.

  • Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

The recent snow sits over weak facet and crust layers in many places. Human triggering in steep terrain remains a real concern, especially in thinner snowpack areas. This problem will be less of a concern in thicker snowpack areas.

  • Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Valid until: Dec 10th, 2019 4:00PM