Avalanche Forecast
Issued: Dec 28th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
shorton,
Avalanche Canada
Conservative terrain selection is recommended because it's possible to trigger large avalanches in isolated areas. We remain uncertain about the exact areas and features of concern.
Summary
Confidence
Weather Forecast
Generally dry and windy weather until Friday.
MONDAY NIGHT: Partly cloudy, strong west wind, temperatures around -12 C.
TUESDAY: Mix of sun and cloud, strong southwest wind, temperatures around -8 C.
WEDNESDAY: Mix of sun and cloud, moderate southwest wind, temperatures around -8 C.
THURSDAY: Cloudy with light flurries and up to 5 cm of snow, strong west wind, temperatures around -8 C.
Avalanche Summary
No recent avalanches have been reported, although there were a few large human-triggered persistent slab avalanches in the Cariboos over the weekend (on northeast slopes near treeline).
The persistent slab avalanche problem is now a low-probability/high-consequence situation. There were many notable avalanches between Dec 18-20 including natural, accidental, and remotely triggered avalanches up to size 2.5 at Pine Pass, Torpy, and Tumbler Ridge. There have not been any avalanches on persistent weak layers in the past week, however snowpack observations suggest these layers may still be reactive in certain isolated areas.
Snowpack Summary
Open terrain is heavily wind affected with potentially reactive wind slabs on steep slopes. 30-50 cm of settled snow sits above a mix of interfaces that were buried in early December. In some (but not all) terrain these interfaces may be composed of weak surface hoar or weak crusts and facet layers, creating a persistent slab avalanche problem. We do not see a clear pattern in which parts of the region or which types of terrain this problem is still a concern. Between Dec 18-20 there was compelling evidence of this problem around Pine Pass, the McGregors, and Tumbler Ridge. This problem has not been found at Renshaw, but has been found in the surrounding areas near McBride. There is no recent information from Kakwa. Overall, uncertainty about these layers make it difficult to have confidence in challenging or complex avalanche terrain without very careful terrain evaluation and an in-depth understanding of local snowpack conditions.
Snow depths are in 150-250 cm around Pine Pass, the McGregors, and McBride and closer to 100-150 cm around Tumbler Ridge. In shallower areas along the eastern slopes there could be weak snow at the bottom of the snowpack that could be a concern in steep rocky alpine terrain.
Terrain and Travel
- Use careful route-finding and stick to moderate slope angles with low consequences.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Problems
Persistent Slabs
Avalanches on weak layers found 30-60 cm below the surface are becoming less likely to trigger, but there has been evidence they are still possible in certain locations. This spatial distribution of this problem is highly variable across the region and across terrain features. The variability and uncertainty about this problem warrants conservative terrain selection. An in-depth understanding of local snowpack conditions is recommended before venturing into challenging or complex avalanche terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Higher elevation terrain is heavily wind affected, with wind slabs likely found on north and east facing slopes.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 30th, 2020 4:00PM
