Avalanche Forecast
Issued: Dec 3rd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet and Deep Persistent Slabs.
ahanna,
Avalanche Canada
Alpine temperatures dip back down to a more seasonal sub-zero in a brief cooling trend Friday. The sun will be shining so still keep an eye on those steep south-to-west slopes in the afternoon, as solar triggered loose snow avalanches are still possible.
Summary
Confidence
Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.
Weather Forecast
Thursday night: Partly cloudy with brief flurries, moderate southwest wind, temperature inversion dissipating, freezing level valley bottom.
Friday: Mix of sun and cloud, moderate west wind, freezing level valley bottom in most areas, 1500 m in the far north of the region. Strong temperature inversion re-establishing late in the day with above freezing air 2000-3500 m.
Saturday: Mix of sun and cloud, moderate southwest wind, strong temperature inversion with above freezing air 2000-3500 m.
Sunday: Sunny, moderate southwest wind, strong temperature inversion returns with above freezing air 2000-3500 m starting to break down.
Avalanche Summary
Loose wet avalanches up to size 1-2 likely occurred during the initial warmup on Wednesday.
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!Â
Snowpack Summary
Solar radiation coupled with a strong temperature inversion has formed a melt-freeze crust on solar aspects at treeline and above. Alpine surfaces are predominantly wind affected, with soft snow still to be found in shady, protected areas at lower elevations.
A couple of layers of feathery surface hoar crystals exist in the upper snowpack. Just 10 cm below the surface, the first of these layers has likely broken down in areas where the surface warmed up on Wednesday. Another patchier layer of smaller crystals may sit beneath 40-60 cm of old wind slab.
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
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Be alert to conditions that change with aspect and elevation.
- Conditions may have improved, but be mindful that deep instabilities are still present.
Problems
Loose Wet
Although the alpine air temperature isn't as warm as previous days, loose wet avalanches may still be observed on steep sun exposed slopes in the afternoon.
Aspects: East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A crust sits near the base of the snowpack. Although we haven't had any reports of avalanche activity on this layer during the recent warming event, there is potential for large avalanches to be triggered on this layer by:
- large loads such as cornice falls or smaller loose wet avalanches
- human traffic in thin, rocky areas in the alpine
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 4th, 2020 4:00PM
