Avalanche Forecast
Issued: Dec 19th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Storm Slabs.
rgoddard,
Avalanche Canada
Manage your terrain and keep an eye out for the persistent slab problem as you enjoy the fresh snow.
Signs of instability like whumpfing and shooting cracks are a clear indication to back off for the time being.
Summary
Confidence
Avalanche Summary
No new avalanches reported in the last 24 hours other than some minor sluffing.
Avalanche activity is tapering off what it was last week when the mid-November layer was very reactive, producing large avalanches in our region and that of our neighbours'. This layer should still be a concern and can be triggered in areas with a shallow snowpack or in certain terrain such as convex rolls.
Snowpack Summary
The top 10 to 25 cm of our snowpack is of low-density unconsolidated snow that sits on a buried surface hoar layer in sheltered areas and a sun crust on the solar aspect. The snow becomes slightly more consolidated after these layers until 35 to 45 cm below the surface is reached where another weak, created in early December, can be found. This layer is made up of surface hoar in sheltered areas and a thin sun crust in open south-facing terrain.
The layer that is still the main concern, is that of mid-November. It is made up of large surface hoar crystals, facets, and a melt-freeze crust and can be found up to 80 cm deep. This layer has been reactive at treeline between 1700 to 2200 m, on all aspects.
Below the mid-November layer is a generally weak, faceted snowpack. Snowpack depths average 80 to 160 cm in the alpine.
Weather Summary
Monday Night
Cloudy with clear periods, no accumulation, 10 to 20 km/h southwest wind, -22 C at 1500 m.
Tuesday
Mostly cloudy, up to 13 cm accumulation, 15 km/h south winds, -21 C at 1500 m.
Wednesday
Mostly sunny with cloudy periods, no accumulation, 15 to 22 km/h northeast wind, temperature -25 C at 1500 m.
Thursday
Sunny, no accumulation, 10 km/h south winds, -23 C at 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Don't let the desire for deep powder pull you into high consequence terrain.
- If triggered, loose dry avalanches may step down to deeper layers resulting in large avalanches.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Persistent Slabs
There are now two persistent weak layers within the snowpack.
A 35 - 45 cm soft slab sits above a weak layer of surface hoar on shaded aspects and crust on steep solar aspects.
A second weak layer of surface hoar and facets from mid-November is buried down 50 to 80cm in the region.
While avalanche activity has tapered off on these layers they likely remain rider triggerable in specific sheltered terrain features at treeline and below.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
Low density snow continues to accumulate on a wide variety of surfaces where bonding is not likely to occur. Moderate wind that is to accompany this new snow is likely to redistribute this snow and create fresh wind slabs.
Beware of smaller loose dry avalanches building a load big enough to trigger weak buried layers and creating larger avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 20th, 2022 4:00PM
