Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Precipitation amounts will be determined by the track of the incoming storm. Local intense snowfall is possible.
While limited snowfall is expected overnight, rapid loading could occur Sunday.
The persistent slabs have remained sensitive to triggering since the last storm. Natural activity on these layers is likely to occur.
Confidence
No Rating
Avalanche Summary
Avalanche control along the Sunshine road Friday produced persistent slab avalanches to size 2.5 on mainly south-facing targets.
Thursday , a skier-triggered a size 2.5 slab on the persistent facet layers at Quartz Hill in the Sunshine Backcountry. This slab averaged 50cm deep but was as thick as 90cm.
Saturday, skiers north of Dolomite Peak triggered a persistent slab that buried one skier.... more to come...
Snowpack Summary
On shaded aspects, 10-15cm of snow has accumulated through the week while several superficial crusts are found on solar aspects.
Persistent weak layers of mainly facets (Feb. 22nd / Jan. 30th) are buried 20 / 50cm deep with a faceted mid-pack buried beneath.
In thin areas to the east, basal facets linger at the base of the snowpack while deeper snowpack areas out west are significantly stronger.
Treeline snow depths range from ~75 cm in the east to over 150 cm in the west.
Weather Summary
An atmospheric river sits over BC. Wherever the "nozzle" of this hose ends up pointing, will receive intense precipitation through Monday morning. SW winds will remain in the strong range while freezing levels approach 2000m.
Models favor the nozzle pointing north of the region Saturday evening to deliver only 5-15cm to BYK by Sunday AM before drooping south to bring another 15 - 35cm through Monday AM.
Terrain and Travel Advice
- Avoid avalanche terrain during periods of heavy snowfall.
- Avalanche danger is expected to to increase throughout the day, think carefully about your exit plan from the backcountry.
- Loose avalanches may step down to deeper layers, resulting in larger avalanches.
Avalanche Problems
Persistent Slabs
Over the past week, numerous human and explosive triggered avalanches have occurred on these layers of facets 20 and 50cm deep. With incoming snow and strong winds, the likelihood of both natural and human-triggered avalanches will rise.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1.5 - 3.5
Loose Dry
Strong alpine winds on Saturday triggered many small loose dry events in lee terrain. Expect this activity to continue and spread to lower levels as the storm progresses Sunday.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2
Wind Slabs
Strong SW winds developed overnight Friday and have been moving snow all day Saturday. On solar aspects slabs will sit on suncrusts while on sheltered, shaded slopes they may sit on surface hoar. Expect these fresh, sensitive surface slabs to develop as the storm progresses.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2