Avalanche Forecast
Issued: Dec 2nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.
swerner,
Avalanche Canada
The snowpack doesn't like rapid change. The avalanche danger remains elevated in the alpine due to sustained warm temperatures. Watch for signs of instability and be very conservative with your terrain selection.
Summary
Confidence
Weather Forecast
Thursday: Mix of sun and cloud. Treeline temperatures near +1 and ridgetop wind light from the southwest. Freezing levels 1600 m.
Friday: Cloudy with sunny periods. Treeline temperatures near 0 and ridgetop wind light from the South. Freezing levels near 1400 m with a weak temperature inversion in the alpine.
Saturday: Mix of sun and cloud. Alpine temperatures near +3 and ridgetop winds remain light. Freezing levels 1400 m with an alpine temperature inversion.
Avalanche Summary
On Wednesday, numerous loose wet avalanches were reported from NE slopes above 2000 m. These avalanches were up to size 1.5 with no significant propagation.
Have you been out and about in the mountains? If so please submit to the Mountain Information Network (MIN). It doesn't have to be technical it can be as simple as a photo. Photos are especially helpful!
Sending a big thank you to the already submitted MIN's this season. Thanks everyone!
Snowpack Summary
It's a very dynamic period and the snowpack doesn't like rapid change.
Recent sun and warm air in the alpine on Wednesday likely had the greatest impact on the upper snowpack, showing signs of instability and promoting further slab development and cohesion. This may be most concerning where these slabs sit above an old thin crust on south aspects and feathery surface hoar crystals in wind-sheltered areas.
Northerly aspects will likely see fresh wind slab development at upper elevations on leeward slopes and melt-freeze conditions may exist on most aspects at upper elevations.
Treeline snowpack depths sit around 100 to 150 cm in the north and 50 to 100 cm in the south of the region.
Crusts from mid-and early-November are generally found 30 cm below the snow surface and 30 cm up from the ground, respectively. While they are still showing results in snowpack tests, most older reports indicate that the bonds at the interfaces with these crusts are improving, but a lot of uncertainty still exists with limited observations. Triggering a slab above this layer may be more likely on south-facing slopes and in shallow, rocky, snowpack areas in the alpine.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Wind Slabs
Recent wind has varied from south to northwest so watch for old and new wind slabs on a variety of aspects, especially at ridge crests and on rollovers.
Aspects: North, North East, East, South East, South, South West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
If the sun is out loose wet avalanche activity may exist especially in alpine locations where the air temperatures may be warmer.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
A crust exists near the base of the snowpack. A lack of decisive data on this layer is keeping it on our radar for now. While it's been showing results in snowpack tests in some areas, most reports describe an improving bond to the overlying snow. Potential for full depth avalanches may exist in areas where weak, sugary facets overly this crust, especially in areas of smooth ground cover such as scree slopes, grassy slopes, or rock slabs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 3rd, 2020 4:00PM
