Triggering avalanches remains likely on steep and wind loaded slopes, with the potential for large avalanches due to buried weak layers.
A weak layer composed of weak and sugary faceted grains above a hard melt-freeze crust exists around 60 to 100 cm deep. It has been over a week since the last reported avalanche on this layer, but the likelihood of triggering it may increase during this stormy period.
We are exiting a stormy period that has left new slabs at all elevations. The snow may be reactive in sheltered terrain where it could overlie a weak layer of surface hoar. Strong wind from the southwest has created thicker and touchier deposits in lee terrain features at higher elevations.
The base of the snowpack has been reported as being composed of weak and sugary faceted grains for much of the region. The most likely area to trigger this deep weak layer would be on slopes where the snowpack is thin or transitions quickly from thin to thick, such as near rocky outcrops.
SUNDAY NIGHT: Mostly cloudy skies, moderate south wind, temperatures around -12 C.
MONDAY: Scattered flurries with a trace of new snow, strong south winds, temperatures around -8 C.
TUESDAY: Scattered flurries with 5-10 cm of snow throughout the day, strong south wind, temperatures around -5 C.
WEDNESDAY: Flurries continue with another 5-10 cm of snow, moderate south wind, temperatures around -5 C.
Several natural storm slab avalanches were reported at Hankin on Sunday (see photos and details here). They were on northeast alpine slopes. The weekend's storm likely resulted in natural avalanche activity in alpine terrain across the region and has potentially left storm and persistent slabs reactive to human triggers.
20-40 cm of snow has accumulated since New Year's Day, potentially leaving storm slabs in areas with deeper accumulations and wind affect. In some terrain this new snow may overly a weak and feathery surface hoar layer, particularly in sheltered treeline and below treeline terrain.
Around 50 to 100 cm deep, a hard melt-freeze crust from early December may have weak and sugary faceted grains around it. The last reported avalanche activity on this layer was around Dec 21. The likelihood of triggering this layer may have increased in response to the load of new snow.
The early-November melt-freeze crust may be found near the base of the snowpack and may have weak faceted grains around it. The last reported avalanche activity on this layer was near Smithers on Dec 22. The most likely terrain to trigger it would be in shallow and rocky alpine areas.
