Avalanche Forecast
Issued: Dec 16th, 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.
kdevine,
Avalanche Canada
Continued flurries with strong southwest winds are expected to create fresh wind slabs at upper elevations. Carefully evaluate conditions, avoid wind loaded areas, and seek out sheltered terrain for the best riding quality.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations. Forecast snowfall amounts are uncertain.
Weather Forecast
WEDNESDAY NIGHT - Mainly cloudy with flurries, 5-10 cm, with up to 15 cm expected near Pine Pass / southwest wind, 40-60 km/h / alpine low temperature near -9
THURSDAY - Mainly cloudy with flurries, 5-10 cm / southwest wind, 30-50 km/h / alpine high temperature near -7
FRIDAY - Flurries, 10-15 cm / southwest wind, 60-80 km/h / alpine high temperature near -2 / freezing level 1500 m
SATURDAY - Flurries, 5-10 cm / southwest wind, 60-80 km/h / alpine high temperature near -3 / freezing level 1700 m
Avalanche Summary
There have been no recent avalanches reported in the region.
Snowpack Summary
10-25 cm of recent new snow sits on previously wind affected snow at higher elevations, and on a crust between about 1300-1600 m. Sheltered areas at treeline may now have 15-45 cm of soft snow on the surface. Moderate to strong southwest winds will likely redistribute the new snow, forming wind slabs in the alpine and in open areas at treeline.
A widespread crust layer that may have sugary faceted grains above it can be found near 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. Observations from around Tumbler ridge suggest ongoing concern for this layer in this zone. I suspect the layer to be potentially reactive in northern parts of the region, such as Pine Pass, but do not have observations to back this up.Â
Snow depths are approximately 150 cm around Pine Pass, Torpy and McBride and around 100 cm in the northeast around Tumbler Ridge.Â
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- 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 southwest winds that are expected this week and through the weekend.
Aspects: North, North East, East, South East, North West.
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 17th, 2020 4:00PM
