Avalanche Forecast
Issued: Dec 11th, 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
Storm slabs will remain most reactive where wind has loaded deeper deposits onto leeward slopes. Raise your guard as you transition into wind-affected terrain.
Summary
Confidence
Weather Forecast
Saturday night: Around 5 cm of new snow with local enhancements possible in the south. Moderate southwest wind. Freezing level valley bottom.
Sunday: A mix of sun and cloud, no significant precipitation. Light to moderate southwest wind. Treeline temperatures around -11 C.
Monday: A mix of sun and cloud with isolated flurries. Moderate southeast wind. Treeline temperatures around -8 C.
Tuesday: A mix of sun and cloud. Light southwest wind. Treeline temperatures around -12 C.
Avalanche Summary
We are still awaiting observations of avalanche activity during the storm.
There were two human triggered avalanches involving persistent weak layers last 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
The convective nature of yesterday's storm has resulted in highly variable snowfall amounts throughout the region. Generally, 10-25 cm of new snow from Saturday's storm has seen redistribution by strong wind at upper elevations.
A few potentially concerning layers exist in the mid to lower snowpack. A surface hoar layer observed near Barkerville, and a widespread crust below 1800 m both now sit 40-70 cm deep. An early season crust layer with some weak snow around it can be found 100-250 cm deep in the alpine.
Terrain and Travel
- Start with conservative lines and watch for clues of instability.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Storm Slabs
Storm slabs will be most reactive where deeper deposits have been wind loaded into lee aspects. Avoid these areas until they have a chance to stabilize.
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 12th, 2021 4:00PM
