Avalanche Forecast
Issued: Dec 17th, 2023 4:00PM
The alpine rating is Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeChoose terrain carefully, and investigate for signs of instability and buried layers of weak surface hoar.
The weight of a rider could cause a surprisingly large avalanche on this layer.
Summary
Confidence
Moderate
Avalanche Summary
No new avalanches were reported on Sunday before 4pm. There are very few field observations coming from this forecast area. Remember that a lack of avalanche reports does not necessarily mean a lack of avalanche activity.
If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).
Snowpack Summary
Strong to extreme southwest wind Sunday night into Monday are scouring south and west-facing slopes in the alpine and at treeline down to hard, old snow surfaces. In slightly less windy terrain, any loose surface snow may blow into deeper deposits on north and east facing slopes.
A concerning layer of weak, feathery surface hoar crystals can be found around 30-50 cm deep.
The midpack may contain a few frozen crusts, and the lower snowpack is generally faceted. Average snowpack depths at treeline range from 50 to 100 cm.
Weather Summary
Temperatures may be colder west of Pine Pass.
Sunday Night
Cloudy. No new snow expected. Strong to extreme southwest ridgetop wind. Treeline temperature around -6°C. Freezing level around 750 m.
Monday
Cloudy. 2-5 cm of snow expected. Wind decreasing to light southeast by the end of the day. Treeline temperature around -4°C. Freezing level around 750 m.
Tuesday
Mostly cloudy. 5-10 cm of snow expected. Moderate southwest ridgetop wind. Treeline temperature around -2°C. Possible temperature inversion.
Wednesday
Mostly cloudy. 0-3 cm of snow expected. Strong southwest ridgetop wind. Treeline temperature around -4°C. Possible temperature inversion.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Persistent Slabs
This problem mostly refers to a weak layer buried in early December, but a layer buried mid December could be active around Pine Pass, where storm snow is deeper. Surface hoar is most likely to be preserved in areas sheltered from the wind.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 18th, 2023 4:00PM