Avalanche Forecast
Issued: Dec 13th, 2021 1:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
JSmith,
Avalanche Canada
Shifting winds may form fresh wind slabs on unusual aspects that are likely to human trigger. Pay attention to changing conditions with elevation/aspect and avoid slopes that have been freshly wind-loaded.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
MONDAY NIGHT: Flurries, 5-10 cm / Moderate, northeasterly winds / Low of -10 C / Freezing level surface.
TUESDAY: Flurries, 3-10 cm / Light, southwesterly winds / High of -6 C / Freezing level 300 m.
WEDNESDAY: Mix of sun and cloud / Light, southwesterly winds / High of -6 C / Freezing level 300 m.
THURSDAY: Mostly cloudy / Moderate, northwesterly winds / High of -6 C / Freezing level 300 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
The 10 cm of new snow and shifting moderate northeasterly winds forecast for Monday night may form fresh wind slabs on all aspects. Beware of wind slabs on non-typical aspects.
Monitor for changing conditions as you move into wind-exposed terrain and pay attention to cracking or hollow sounds.
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
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of highly variable recent wind loading patterns.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- 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.
Problems
Wind Slabs
Forecast snow and shifting northeasterly winds Monday night may form fresh wind slabs on all aspects. Beware of wind slabs on non-typical aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
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
Valid until: Dec 14th, 2021 1:00PM
