Avalanche Forecast
Issued: Dec 10th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
New snow and wind are forming touchy slabs. Stick to simple terrain and be aware of what is above you at all times.
Summary
Confidence
High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
Friday night: 5-15 cm of new snow. Strong to extreme southwest wind. Freezing level climbing to 900 m.
Saturday: 10-20 cm of new snow. Strong southwest wind easing in the afternoon. Treeline temperatures around -8 C. Freezing level 800 m.
Sunday: 5-15 cm overnight then a mix of sun and cloud. Moderate southwest wind. Treeline temperatures around -10 C. Freezing level valley bottom.
Monday: Flurries with sunny periods. Moderate southeast wind. Treeline temperatures around -10 C. Freezing level valley bottom.
Avalanche Summary
While there have been no avalanches reported in the past few days, there was likely some avalanche activity in the alpine during Wednesday's storm. Wind slab avalanches remain a concern at treeline and alpine elevations.
There were two human triggered avalanches involving persistent weak layers earlier this week. One was a size 2 avalanche triggered in a north-facing bowl near Barkerville. This avalanche is suspected to have occurred on a 50 cm deep surface hoar layer. The other was triggered near McBride and released on a steep rocky slope near treeline (see this MIN report). The failure layer was likely an early season crust/facet layer.
Snowpack Summary
15-30 cm of new snow falls amid strong wind over previously wind affected surfaces at upper elevations.
Storms over the past week delivered a total of 20-40 cm on top of a few potentially concerning layers including isolated layers of surface hoar around treeline and a slippery crust below 1800 m.
An early season crust layer with some weak snow around it can be found 100-250 cm deep in the alpine. There is also evidence of a weak surface hoar layer 50 cm deep in the Barkerville area.
Terrain and Travel
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
- Be careful to keep storm day fever from luring you out into bigger terrain features.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
Problems
Storm Slabs
New snow and wind form fresh storm slabs over previously wind affected surfaces. Be aware of the potential for deeper than expected storm slabs around treeline due to the presence of a buried crust in the upper snowpack below 1800 m.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A few recent reports of avalanches have raised concern about buried weak layers in the Cariboos. The main concern is a buried surface hoar layer near Barkerville, especially on north-facing slopes. We suggest conservative terrain selection as these layers could remain reactive with the added weight of new snow.
Aspects: North, North East, East, North West.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 11th, 2021 4:00PM
