Avalanche Forecast
Issued: Dec 6th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
ahanna,
Avalanche Canada
The new snow is not expected to bond well to old surfaces. Watch for sluffing out of steep terrain, and fresh storm slabs in wind loaded lee features.
In areas where more than 20 cm falls, avalanche danger will rise to CONSIDERABLE at alpine and treeline elevations.
Summary
Confidence
Weather Forecast
The incoming storm will deliver the bulk of its goods on Monday night. Highest snowfall amounts on Monday will be in the area west of Valemount.
Sunday night: Up to 5 cm new snow, strong southwest wind, freezing level 1200 m.
Monday: Up to 10 cm new snow, strong south wind, freezing level 1400 m.
Tuesday: 15-30 cm new snow, strong wind easing to light southwest, freezing level 1500 m.
Wednesday: Flurries, light west wind, freezing level 1000 m.
Avalanche Summary
On Monday, small storm slabs may be triggerable in freshly wind loaded lee features at upper elevations. Loose dry sluffing may be observed out of steep terrain, especially with human traffic.
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
5-15 cm of new snow falls ontop of a melt-freeze crust on south aspects and widespread surface hoar. Generally speaking, new snow does not bond well to these types of surfaces.
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
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Dial back your terrain choices if you are seeing more than 20 cm of new snow.
Problems
Storm Slabs
The new snow is not expected to bond well with old surfaces such as crusts and surface hoar.
Small loose dry sluffing may be observed out of steep terrain, especially with human traffic. Look for signs of instability like shooting cracks to identify where the snow is starting to show slab character. Small storm slabs may be triggerable in freshly wind loaded lee features at upper elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
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 under the current conditions, we're reluctant to throw it out altogether, especially with significant accumulations of new snow on the horizon. 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
Valid until: Dec 7th, 2020 4:00PM
