Avalanche Forecast
Issued: Dec 18th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
lbaker,
Avalanche Canada
Though avalanche activity on the persistent weak layers has decreased it is imperative that backcountry users continue to use extra caution around these layers. Maintain good travel habits and use decision-making tools.
This week's cold temperatures coupled with the shortest daylight hours of the year can make any sort of incident (even broken equipment) an epic. Be careful not to ruin the rest of your season with frozen toes.
Summary
Confidence
Moderate
Avalanche Summary
On Saturday a size one, skier accidental, wind slab avalanche was reported on a southeast aspect at 2300 m.
On Friday in the Northern Selkirks skiers remotely triggered a size 2 avalanche which sympathetically triggered a 2.5 avalanche on an adjacent path. These avalanches occurred at 2300m on a southeast aspect. Throughout the region, several machine accidental avalanches were reported to size 2.
On Thursday, skiers remotely triggered a large size 2 avalanche in the Monashees north of Hwy1. This avalanche occurred around 1900 m on an east aspect and was triggered from about 40 m away by skiers on a low-angle bench.
Snowpack Summary
Snowpack depths at treeline range from 100 - 150 cm. In the alpine, snowpack depths are highly variable from extensive wind-affect in many locations.
Surface: 5 cm of new snow now overlies 5-8 mm surface hoar in sheltered areas. On steep solar slopes, new snow overlies a sun crust. Moderate westerly winds have built thin wind slabs in alpine lees.
Upper-pack: Cold temperatures are faceting the upper snowpack. 40-50 cm settling snow overlies a weak layer of 5 mm surface hoar in sheltered and shaded terrain and a sun crust on sunny south-facing slopes.
Mid-pack: Buried 60-90 cm deep, is a persistent weak layer of surface hoar, crust, and faceted crystals. This layer has been most reactive at treeline between 1700-2200 m, but it was also observed as low as 1450 m and on all aspects.
Lower-pack: Below the mid-November layer is a generally weak, faceted snowpack.
Weather Summary
Sunday Night
Scattered clouds clear in the night. Isolated flurries south of Revelstoke, trace accumulation. Light northeasterly ridgetop winds. Expected temperatures near -27 C this afternoon and tonight.
Monday
Mainly sunny. Temperatures at 1500-1800 m will hover near -20 to -25 C. Light easterly ridgetop winds.
Tuesday
Sunny with cloudy periods. At 1500m temperature will be around -23 C and winds are moderate southwesterly, gusting to 40 km/h.
Wednesday
Sunny. Light northerly ridgetop winds and temperatures are around -25 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Avoid making assumptions about this layer based on the presence of aggressive tracks on adjacent slopes
Problems
Persistent Slabs
There are two persistent weak layers within the snowpack: 30-50 cm of snow covers a weak layer of surface hoar on shaded aspects and crust on steep solar aspects; many avalanches failed on this layer last week.
A second weak layer of surface hoar and facets from mid-November is buried 60-90 cm in the region; this layer has recently surprised both professionals and recreationists with large human-triggered avalanches.
Read our featured blog to learn more about how to manage a persistent slab problem when traveling in the backcountry.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Moderate westerly winds have built thin wind slabs at higher elevations. Be cautious when transitioning into wind-affected areas, especially around ridge crests and roll-overs in steep terrain.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 19th, 2022 4:00PM
