Fresh storm slabs are expected to be reactive to human triggers on Friday, especially in wind-affected terrain.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
THURSDAY NIGHT: 10-15 cm new snow / Strong southwesterly ridgetop winds / Freezing level around 1500 m.FRIDAY: 5-15 cm of new snow / Strong southwesterly ridgetop winds / Freezing level around 1500 m.SATURDAY: Mostly sunny / Light southwesterly ridgetop winds / Freezing level rising to around 1800 m.SUNDAY: Mostly sunny / Light southwesterly ridgetop winds / Freezing level rising to around 2000 m.
Avalanche Summary
Explosive control work near Fernie on Wednesday produced small slab avalanches up to size 1.5. Failing cornices also triggered size 2 slab avalanches on northerly aspects. Thursday's storm is expected to create touchy storm slabs reactive to human triggers.
Snowpack Summary
10-15 cm of new snow on Thursday is sitting on a sun crust on solar aspects.In the upper to mid snowpack, a surface hoar layer buried mid-February is now 80 to 100 cm below the surface on sheltered northerly aspects. Deeper in the snowpack, the widespread mid-December and late November weak layers are composed of a combination of crusts and sugary facets which are down 200-300 cm.
Problems
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.