Avalanche Forecast
Issued: Dec 17th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Wind Slabs and Loose Dry.
CJ,
Avalanche Canada
Recent new snow and wind combined with the weak basal facets are keeping the avalanche hazard elevated this weekend.
A deep freeze has arrived with treeline temperatures staying in the -20 to -30°C range. Be prepared for the unexpected with extra warm clothing!
Summary
Confidence
Avalanche Summary
Over the past few days, local ski hills have triggered deep persistent slabs up to size 2 with explosives, and sometimes with a ski cut after the explosive failed to trigger the slope. Parks Canada forecasters noted large whumpfs in the Sunshine Backcountry on Tuesday and in the O'Hara region on Thursday. No new naturals have been observed for the past few days.
Snowpack Summary
5-15 cm of new low density snow sits over a layer of recent surface hoar, with NW winds forming small new wind slabs in lee areas of the alpine. The upper 20-60 cm of snow has formed a soft slab over the very weak base of facets and depth hoar. Snowpack depths at treeline range between 60 and 120 cm. Below treeline the entire snowpack is weak and faceted and dry loose sluffs may be triggered in steep features.
Weather Summary
A surface ridge of high pressure will continue to build on Sunday with a few flurries expected in the moring as the ridge establishes itself. Winds will be light and temperatures will reamin COLD with alpine highs of -25 to -30°C.
Terrain and Travel Advice
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Deep Persistent Slabs
A 20-60 cm slab has formed over the very weak basal facets, with thin crusts at the interface on some solar slopes. Human triggering is likely on any steep slopes where a cohesive slab of snow is found over the facets. This problem will remain for the foreseeable future. Below treeline, the snowpack is very weak and unsupportive.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
5 to 15 cm of low density snow with moderate to strong NW winds have formed small new wind slabs in lee areas at upper elevations. These new wind slabs will likely remain susceptible to human triggering for a few days. If triggered they could step down to the basal weak layers resulting in larger avalanches.
Aspects: North, North East, East, South East, South.
Elevations: Alpine.
Likelihood
Expected Size
Loose Dry
Cold temperatures and a shallow snowpack have resulted in heavily faceted snow at lower elevations. In sheltered areas the snowpack has very little structure and it is possible for skiers or climbers to trigger small loose dry avalanches in steep terrain.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 18th, 2022 4:00PM
