Avalanche Forecast
Issued: Jan 12th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
kdevine,
Avalanche Canada
Wind slabs may be hidden under a dusting of new snow, and could exist on all aspects due to recent variable wind directions. Watch closely for signs of instability such as whumpfing, cracking, and recent avalanches.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
TUESDAY NIGHT - Mainly cloudy / light west wind / alpine low temperature near -10Â
WEDNESDAY - Mainly cloudy with a few flurries, up to 5 cm / light to moderate west wind / alpine high temperature near -9
THURSDAY - Mainly cloudy / moderate southeast wind / alpine high temperature near -5Â
FRIDAY - Mainly cloudy with a few flurries, 5 cm / moderate to strong southwest wind / alpine high temperature near -6
Avalanche Summary
Wind slabs may continue be reactive to human triggers on Tuesday, especially at upper elevations.Â
There were a few explosives triggered size 2 avalanches reported near the southern boundary of the region on Sunday.
On Saturday, explosive control work near Ningunsaw (just outside the region) produced several wind slabs to size 2.5 and one size 3 deep persistent slab failing on weak facets near the base of the snowpack. Another reminder of the "low probability; high consequence" scenario that persistent slab problems often create.
Snowpack Summary
5 cm of fresh snow overnight is likely sitting on widespread wind slabs in open terrain in the alpine and at treeline. These wind slabs may sit on a weak layer of surface hoar that was recently buried at treeline and below treeline.
In the south of the region, another weak layer of surface hoar that was buried around the New Year has been reported down 50-70 cm in sheltered areas.
The lower snowpack has two crusts with potentially weak, faceted snow around them. Reports from the Smithers area suggest the upper crust is 70-140 cm below the surface and has shown signs of being possible to trigger from shallow areas. The deeper crust is near the bottom of the snowpack, and is most likely to trigger from steep, rocky slopes, with a shallow or thin to thick snowpack.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Recent new snow may be hiding windslabs that were easily visible before the snow fell.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.
Problems
Wind Slabs
Wind slabs may continue to be reactive to human triggers at upper elevations. They may also be hidden in some areas, under a few cm of fresh snow. Previous winds have been strong to extreme from a variety of directions, so wind slabs could exist on all aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Triggering large avalanches on weaknesses in the lower snowpack remains a possibility. In some areas the concern is weak snow around crusts 70-140 cm deep, while in others it is weak snow near the bottom of the snowpack. Human triggering of these layers are most likely in steep, rocky slopes with a shallow or thin to thick snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 13th, 2021 4:00PM
