Avalanche Forecast
Issued: Dec 5th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Loose Wet.
ahanna,
Avalanche Canada
Temperatures are forecast to remain elevated in the northeast part of the region. Watch for signs of instability like pinwheeling in moist or wet snow.
As temperatures drop below freezing, avalanche hazard will decrease. Make observations and evaluate conditions as you travel.
Summary
Confidence
Weather Forecast
Saturday night: Clear, light to moderate southwest wind, temperature inversion breaking down, freezing level 500 m in most areas, remaining elevated at 2000 m in the northeast of the region.
Sunday: Increasing cloud, light to moderate southwest wind, freezing level 1100 m, 2000 m in the northeast of the region.
Monday: 10-20 cm new snow, moderate to strong south wind, freezing level 1000-1300 m.
Tuesday: 5-10 cm new snow then clearing, wind easing to light southwest, freezing level 1300 m.
Avalanche Summary
Loose wet avalanches size 1-2 likely occurred during the warmup on Wednesday and Saturday.
Our eyes and ears in the mountains are limited this winter due to fewer professional observations. If you go out in the mountains, please share your observations on the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!
Snowpack Summary
A melt-freeze crust on steep solar aspects at treeline and above will soften through the day. On shadier aspects, alpine surfaces are predominantly wind affected, with soft snow still to be found in at lower elevations. Widespread growth of large surface hoar crystals (up to 2 cm!) and surface faceting have been reported. These types of crystals (crust, hoar, facets) that develop on the surface as it sits exposed during prolonged periods of high pressure like this often become a problem once buried by the next snowfall.
The lower snowpack is characterized by a couple of crusts, the most notable of which is sitting near the base of the snowpack, likely surrounded by a weak layer of sugary facets. It is most likely to be reactive to human triggers on south facing slopes and in shallow, rocky areas in the alpine.
Terrain and Travel
- Start on smaller terrain features and gather information before committing to bigger terrain.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
- Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.
Problems
Deep Persistent Slabs
A crust sits near the base of the snowpack. On the one hand, there hasn't been any associated avalanche activity in weeks. On the other hand, it's surrounded by weak crystals and still producing hard results in snowpack tests. Although we don't think it presents an avalanche problem as we enter a cooling trend, we are skeptical where temperatures remain elevated in the northeast of the region. If it were to rear its head, it would most likely be in shallow, rocky areas in the alpine.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Loose wet avalanche activity may persist in the northeast of the region where temperatures remain elevated Sunday. Pinwheeling is a great indicator of a warming snowpack.
Aspects: South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 6th, 2020 4:00PM
