Avalanche Forecast
Issued: Dec 9th, 2019 4:04PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
Conrad Janzen,
Parks Canada
Enjoy the great snow but stick to more conservative ski terrain, minimize exposure to large slopes and avoid terrain traps for the next few days. We have a significant slab over a weak base and it will take some 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
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.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
- Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The recent snow sits over weak facet and crust layers. Numerous natural and explosive triggered avalanches up to size 3 have been observed on these weak lower layers in the past several days. Human triggering in steep terrain remains a real concern.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 10th, 2019 4:00PM
