Avalanche Forecast
Issued: Dec 14th, 2021 1:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
JSmith,
Avalanche Canada
The current persistent slab problem is best managed through conservative terrain choices and disciplined backcountry travel techniques.
Avoid likely trigger spots such as steep, rocky terrain, with a shallow or thin to thick snowpack.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Uncertainty is due to the limited number of field observations.
Weather Forecast
TUESDAY NIGHT: Partly cloudy / Moderate, southwesterly winds / Low of -12 C / Freezing level surface.
WEDNESDAY: Cloudy / Light, southwesterly winds / High of -5 C / Freezing level 500 m.
THURSDAY: Mix of sun and cloud / Light, northwesterly winds / High of -7 C / Freezing level 200 m.
FRIDAY: Mix of sun and cloud / Moderate, northwesterly winds / High of -9 C / Freezing level surface m.
Avalanche Summary
Check out this recent MIN report of a naturally triggered size 3.5 storm slab avalanche reported on Sunday near Mt. Pierce.
In the neighboring Sea to Sky region, we received recent reports of four large (size 2-2.5) explosive-triggered persistent slab avalanches failing on the early December crust/facet layer. These occurred on northwest and northeast aspects in the alpine.
Snowpack Summary
70-90 cm of recent snow and strong winds have formed wind slabs on lee features at treeline and above.
In the north of the region, weak faceted snow can be found 50-70 cm deep on a crust that formed in early December. This layer has shown reactivity in the neighboring Sea to Sky region. This persistent slab problem warrants careful evaluation and conservative route-finding as the recent snow consolidates into a more cohesive slab over the weak layer.
The south of the region has seen substantially higher snow totals over the past week, with areas near the Coquilhalla seeing over a meter of accumulation since Monday. Expect to find deeper snow accumulations above the December crust and anticipate larger slab avalanches.Â
Terrain and Travel
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Uncertainty is best managed through conservative terrain choices at this time.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Problems
Persistent Slabs
In the north of the region, a layer of weak facets (sugary snow) can be found down 50-70 cm near a crust that formed in early December. In the neighboring Sea to Sky region, this layer has demonstrated recent instability, and it may be possible to trigger.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
70-90 cm of recent snow and strong winds have formed wind slabs on lee features at treeline and above.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 15th, 2021 1:00PM
