Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Human-triggered wind slabs are still possible. Use caution in lee areas.
Confidence
Moderate
Avalanche Summary
Lake Louise patrol produced several size 1 wind slabs with explosives today, mostly in the alpine. They also cleaned out D-Gully with a hand charge that produced a size 2, which ran on the ground. This feature hand previously avalanched and reloaded. Sunshine patrol remotely triggered a size 2 deep slab in the Wild West that was 80m wide and 60cm deep.
Snowpack Summary
Widespread wind slabs are present in the alpine and treeline due to last week's storm snow and wind event. The wind slabs overlie the various Jan PWL interfaces of sun crusts, facets, and surface hoar down 80-120 cm. The weaker Nov 16 basal facet layer is down 100-200cm, and produces mod-hard sudden collapse results. Deeper snowpack areas west of the divide are stronger and more supportive than areas to the east.
Weather Summary
Cool temps for the next few days will show the valley not being warmer than -2 and the ridge about -15. Wind will pick up into the strong range from the SW Wednesday morning and will stay elevated through Friday. Snow beginning late on Wednesday will amount to about 10cm late on Thursday.
Terrain and Travel Advice
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Wind slabs up to 80cm deep that were formed by previous wind and storm snow are slightly less sensitive. However, if triggered, these wind slabs still have potential to step down to deeper layers. Remain vigilant in lee areas where wind slabs are more likely.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
Three persistent weak layers formed in January are down 70-100 cm. The biggest concern is triggering these buried suncrusts on steep solar slopes, but weaker facets and isolated surface hoar can be found on the same interface on shaded aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 1.5 - 2.5
Deep Persistent Slabs
Weak facets and depth hoar are present at the bottom of the snowpack. The snowpack is adjusting to the new load from last weeks storm, but natural triggering is still possible. Be especially cautious in thin snowpack areas, which are likely areas for triggering.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 2.5