Avalanche Forecast
Issued: Dec 12th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
mconlan,
Avalanche Canada
Sunny skies may be enticing, but there remains uncertainty as to whether a deeply buried weak layer is a problem in the region; use caution in steep terrain at higher elevations. New wind slabs are expected to form on Monday.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
SATURDAY NIGHT: Mostly clear skies, 20 km/h northwest wind, alpine temperature -14 C.
SUNDAY: Mostly clear skies, 20 km/h southwest wind, alpine temperature -15 C.
MONDAY: Mostly cloudy with light snowfall, accumulation 5 cm, 40 to 60 km/h west wind, alpine temperature -8 C.
TUESDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 40 to 60 km/h southwest wind, alpine temperature -7 C.
Avalanche Summary
A few old slabs were reported around Torpy on Friday in this MIN. Given the looks of the slabs, they likely released quite a few days ago. Otherwise, no other avalanches have been reported recently.
While there have not been any recent reports of deep persistent slab avalanches, we can not rule out the possibility that this problem still lurks in parts of the region. Faceted grains above a crust near the bottom of the snowpack was the likely failure layer in a fatal avalanche near Pine Pass on November 28. With little recent information about this layer it is best to remain cautious around large, high consequence slopes, especially if they are thin and rocky.
Snowpack Summary
Snow depths are approximately 150 cm around Pine Pass, Torpy and McBride and 50-100 cm in the northeast around Tumbler Ridge.Â
The alpine is heavily wind-affected and lower elevations are capped by a hard crust up to around 1300 to 1600 m. Sheltered areas at treeline may still have 5 to 20 cm of soft snow on the surface. Monday's strong wind will likely form new wind slabs in exposed terrain.
A widespread crust layer that may have sugary faceted grains above it can be found at the bottom of the snowpack. Uncertainty remains about if and where this layer is a problem. Recent observations from the McBride area suggest the snow is well-bonded to this crust. There is no recent information from northern parts of the region, such as Pine Pass and Tumbler Ridge, where this layer was a problem earlier this season.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Wind Slabs
Triggering wind slab avalanches remains possible at higher elevations, especially on freshly wind-loaded terrain features. New wind slabs are likely to form during periods of strong wind on Monday.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
We are uncertain about where the early-November crust has weak faceted grains above it, and if this layer remains as a problem. Our limited information suggests this problem is more likely found around Pine Pass and the eastern slopes of the Rockies. Given our lack of field observations, the prudent choice is to approach any big open slope with caution, especially slopes that are rocky and have variable snowpack depths.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 14th, 2020 4:00PM
