Avalanche Forecast
Issued: Dec 13th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Wind Slabs.
JSmith,
Avalanche Canada
There have been reports of large explosive triggered avalanches failing on sugary facets near the ground during this past week. Cornice falls or smaller avalanches in motion may have the potential to step-down to these deeper layers, producing large, destructive avalanches.
Summary
Confidence
Weather Forecast
SUNDAY NIGHT: Cloudy / Strong, southwest ridgetop wind / alpine low temperature -16 / Freezing level valley bottom.
MONDAY: Cloudy / Moderate, southwest ridgetop wind / alpine high temperature -12 / Freezing level valley bottom.
TUESDAY: Snow; 3-5 cm. / Moderate, southwest ridgetop wind / alpine high temperature -11 / Freezing level valley bottom.
WEDNESDAY: Cloudy with isolated flurries; 0-3 cm. / Strong, southwest ridgetop wind / alpine high temperature -8 / Freezing level valley bottom.
Avalanche Summary
There have been a couple reports of large(size 3) explosive triggered avalanches failing on sugary facets near the ground in the north of this region near Tatlatui provincial park during this past week. These have been triggered by both explosives and heavy snow loading during the last storm.
Data in this region is very sparse. Please submit your observations to the Mountain Information Network.
Snowpack Summary
Recent winds from a variety of directions have reverse loaded some slopes, creating wind slabs on typically windward features at treeline and above.
Up to 20 cm of recent snow fell at upper elevations and may sit above a newly formed crust. This new snow may have a poor bond to the underlying crust and be reactive to human triggering.
In many treeline and below treeline areas, the combination of above freezing temperatures and rain saturated the entire snowpack. As a result, the snow has melted fast at lower elevations, and snowpack depths have seen rapid settlement.
At the base of the snowpack sits the early November crust with weak, sugary facets below. These facets near the bottom of the snowpack have produced very large deep persistent slab avalanches near the Ningunsaw and Tatlatui Provincial Parks. Although the extent of this snowpack structure in the region is not well-known, it may be more prevalent in northern half of the region.
Snowpack depths vary substantially with aspect, elevation, and wind exposure. Below treeline the terrain may still be below the threshold for avalanches.
Terrain and Travel
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid lee and cross-loaded terrain.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Deep Persistent Slabs
Cornice falls or smaller avalanches in motion may have the potential to step-down to these deeper layers, producing large, destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Recent winds from a variety of directions have formed wind slabs on typically windward features at treeline and above. Use caution when transitioning into wind affected terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 14th, 2020 4:00PM
