Avalanche Forecast
Issued: Dec 15th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
CB,
Avalanche Canada
If Alpine winds speeds reach moderate, gusting to strong on Friday, avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
Have a look at a blog from the Avalanche Canada forecasters on how to manage a persistent slab problem in the backcountry.
Summary
Confidence
Moderate
Avalanche Summary
Isolated natural sluffs and small avalanches up to size 1.5 have been observed over the past few days along the highway corridor.
A skier triggered a sz 1.5 near the Dome col on Monday.
More reports came in about unsupported pockets of soft slab failing on Dec 5 and Nov 17, mainly occurring around treeline and morainal features. Most avalanches were small (sz 1 or less), but still large enough to bury a person in a terrain trap.
Scary persistent slab incident in the RMR backcountry from Monday; see MIN report.
Snowpack Summary
Surface conditions include sun crust on steep, solar aspects TL and Alp, and growing surface hoar. In general the snowpack is faceting with continued cool conditions, this combined with a below average snowpack is making for a unusually weak Selkirk snowpack with lots of BTL terrain roughness(ie. alders, rocks, trees, creeks).
Settled HST over the Dec 5 persistent weak layer in down 30-40 cm. It consists of surface hoar, preserved stellars, facets, and a thin sun crust on steeper solar aspects.
The Nov 17th Surface Hoar is now buried 60-90cm and continues to produce sudden results in snowpack tests.
Weather Summary
A ridge of high pressure will start to leave the region as a arctic front moves into the interior Saturday. This weather system will bring cloud cover, Northerly winds and light snow.
Friday: Cloudy, Nil precip, Alp High -10*C, Ridge wind NW 20km/h gusting to 40, fz level 400m
Saturday: Isolated flurries w/trace snowfall amounts, Alp High -12*C, Ridge wind NW 10-30 km/h
Sunday: Isolated flurries w/trace snowfall amounts, Alp High -24*C, Ridge wind E 15 km/h
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Exercise caution on steep, unsupported slopes.
Problems
Persistent Slabs
The Nov 17 and Dec 5 surface hoar are down ~75cm and ~35cm respectively, and most reactive around tree line. These layers give 'sudden' results in snowpack tests. If triggered, these layers can produce avalanches across continuous and broken features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 16th, 2022 4:00PM
