Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
Forecast snowfall amounts are uncertain but moderate to strong winds will be sustained; expect avalanche hazard to increase. Both natural and human triggered slabs have been reported near treeline.
Weather Forecast
A Southwesterly flow arrives midday Sunday favoring Northern areas. Models disagree on snow quantities but 10 to 25cm should be the range. Generally temps will remain in the -5 to -10C range but a brief spike in freezing level would not be a surprise with the arrival of this moist pacific air. Moderate to strong winds will continue through Sunday.
Snowpack Summary
Light flurries again today with moderate West winds. 15 to 25cm of storm snow in the last 72 hours. The alpine snowpack ranges from 50-100 cm across the region with the main feature to watch in the snowpack being a layer of facets now buried 25 to 40 cm . Below 2700m these facets sit above a temperature crust that was buried on Halloween.
Avalanche Summary
Continued reports of storm and wind slab activity are coming in; most notably a sz 2 slab at treeline just west of the Bourgeau Left ice climb reported by the Sunshine patrol. This slab was undoubtedly triggered by sustained wind loading late in the day Friday and is likely to have failed on facets over the Halloween crust.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Sunday
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.