Avalanche Forecast
Regions: Banff Yoho Kootenay.
Tricky conditions currently and some variability throughout the region. Alarming sudden results on the Dec cr in Kootenay today. Several natural and explosive triggered avalanche over the past few days...with more wind on the way to load slopes...
Weather Forecast
Winds increase Wednesday night with snow beginning on Thursday. 5-10 cms of snow is expected with strong W alpine winds and warming temperatures through the day. Friday looks to be overcast with moderate NW winds and light snow.
Snowpack Summary
10-15 cms of low density snow with little wind effect sits on top of windslabs in the alpine and in some treeline areas. These overlie facets in many places resulting in wide propagations in recent avalanches. The Dec. 2 crust and facets are generally 60-90cm deep in the snowpack. Some thin snowpack areas have lingering basal depth hoar and facets.
Avalanche Summary
In the past 48 hrs a small avalanche cycle to size 2 occurred. Avalanche control in Yoho Tuesday produced slabs with every shot. Most were failing on a windslab or facet layer 40-60cm deep and then entraining facets in the track. One stepped down to the November facets ~ 180 cm deep.
Confidence
Due to the quality of field observations
Avalanche Problems
Wind Slabs
Wind Thursday will move recent new snow (10-25 cms) adding to the previous windslabs in alpine and treeline terrain. In some areas, these have been enough to initiate deeper layers in the snowpack once triggered.
- Minimize overhead exposure during periods of heavy loading from new snow, wind.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1.5 - 3
Persistent Slabs
This problem represents both the Dec. 2nd crust/ facet layer (treeline and below) and layers of faceted snow that were formed during the late December cold snap (all elevations). If triggered, either layer will result in large avalanches.
- Forecasters are operating with alot of uncertainty at this time.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 2 - 3