Avalanche Forecast
Issued: Dec 29th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Persistent Slabs.
SH,
Avalanche Canada
The deeper weak layers are active and human-triggered avalanches are likely. A special avalanche warning has been issued which includes our region.
Avalanche control will be conducted on Mounts Stephen, Field, and Dennis in Yoho on Dec. 30, 2022. These areas are closed to any activities during this time. Click here for maps of the closure zones.
Summary
Confidence
Avalanche Summary
Avalanche control over the last couple of days on has produced large avalanches up to size 3. These were on Mt. Bourgeau along the Sunshine Village Access Road, Mount Whymper, and Simpson. Some were initiated on the Dec. 17 interface, with many stepping down to the basal facets. Visitor Safety Specialists remote-triggered a size 2 from a ridge on Mt. Simpson, and there was also a skier-triggered incident on Bow Peak which luckily just resulted in lost gear. A natural cycle over the last 24-48 hours up to size 2.5 was observed on a flight along the range.
Snowpack Summary
Slabs sit atop a weak layer of facets and surface hoar (Dec. 17th interface). Below this, the snowpack is generally facetted with the largest facets and depth hoar near the bottom. Snowpack depths at treeline range from 80-150cm throughout the region.
Weather Summary
On Friday, increasing clouds with minimal accumulations and West ridgetop winds 20-40km/h. Freezing levels will remain at valley bottom. On Friday evening, another wave from the Pacific will bring snow to the region, with 5cm forecast for places such as Little Yoho.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Deep Persistent Slabs
Much of the bottom half of the snowpack is very weak and faceted. Avalanches have been initiated on this layer, or starting higher in the snowpack and "stepping down" to the basal facets causing large avalanches
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Slabs typically 25-60cm thick overly faceted snow (Dec. 17th weak layer) that was on the surface during the prolonged deep freeze. If initiated, the big concern is that it can step down to the deeper weak layers. Below treeline the problem exists only where there is a slab overlying the deeper weak layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 30th, 2022 4:00PM
