Avalanche Forecast
Issued: Dec 25th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Deeply buried weak layers continue to be a concern. If triggered, avalanches running on these weak layers will likely be large and destructive. Choose conservative terrain.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
FRIDAY NIGHT: Cloudy with isolated flurries, light south wind, alpine temperature near -10 C.
SATURDAY: Scattered flurries, accumulation 5-10 cm, light to moderate southwest wind, alpine temperature near -8 C.
SUNDAY: Mainly cloudy with sunny breaks, light to moderate west wind, alpine temperature near -8 C.
MONDAY: Mix of sun and cloud, light west wind, alpine temperature near -10 C.
Avalanche Summary
Thursday's reporting showed a naturally triggered size 3.5 persistent slab avalanche running in the alpine on a southeast aspect. There was also a report of size 2.5 naturally triggered windslab in the alpine on a south aspect.Â
On Wednesday there was a report of several size 3 to 4 explosives controlled persistent slab avalanches in the south of the region along the Highway 1 corridor. These ranged from south and east aspects to northeast running from the alpine to the valley floor.Â
Snowpack Summary
Snow falling last week has been redistributed by winds blowing from a veriety of directions at upper elevations. Underneath this storm snow there is a sandwich of weak layers which are widespread throughout the region.
About one meter below the surface is the mid December surface hoar. This layer has recently been sensitive to human triggering.
Below that lies the early December persistent weak layer, it's about 80 to 140 cm below the surface. This weak layer is a mixed bag that often presents as surface hoar and facets sitting on top of a supportive crust. This is a nasty weak layer, when avalanches fail on it, they have been large and destructive. Smaller avalanches in motion can step down to this one too.Â
Terrain and Travel
- Uncertainty is best managed through conservative terrain choices at this time.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Wind Slabs
Wind switching directions has created wind slabs on a variety of aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A slab rests on a persistent weak layer which has the capacity to propagate avalanches across terrain features. Although the likelihood of triggering a persistent slab avalanche is reducing, the potential for triggering a high consequence avalanche should still be top of mind in your decision making process.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 26th, 2020 4:00PM
