Avalanche Forecast
Issued: Dec 12th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
Wind slabs will be the main concern on Monday. Be on the lookout for drifted snow and signs of instability like shooting cracks as you enter wind-affected terrain.
Summary
Confidence
Weather Forecast
Sunday night: A trace of new snow. Moderate southerly wind. Treeline temperatures around -10 C.
Monday: A mix of sun and cloud with isolated flurries up to 5 cm. Light to moderate southeast wind. Treeline temperatures around -9 C.
Tuesday: A mix of sun and cloud. Light northwest wind. Treeline temperatures around -15 C.
Wednesday: A mix of sun and cloud. Light southeast wind. Treeline temperatures around -13 C.
Avalanche Summary
Check out this MIN report, describing low elevation wind loading and touchy conditions near Barkerville on Sunday. We have not received reports of any other avalanche activity in the region.
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 the storm on the weekend has resulted in highly variable snowfall amounts throughout the region, generally ranging from 10-25 cm. While we don't have any recent observations from the alpine, we expect to see lots of redistribution of recent snow by wind, as wind loading was observed even at low elevations in the trees in this MIN report from near Barkerville on Sunday.
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
- Be careful as you transition into wind affected terrain.
- Start on smaller terrain features and gather information before committing to bigger terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Wind loading has been reported at low elevations in the trees. Watch for signs of instability in drifted snow. As wind direction shifts southeast on Monday, watch for changes in loading patterns.
Below treeline, recent snow may remain reactive longer than normal where it sits on a weak layer over a crust. You can dig down to investigate the bond between the thick crust and overlying snow.
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 13th, 2021 4:00PM
