A new surface hoar layer is now shallowly buried. Avalanche danger will increase as it gets buried deeper. If snowfall amounts are greater than expected on Saturday, avalanche danger will be higher than forecast.
Weather Forecast
The weather is changing as a low pressure system moves in. Light flurries, temps from -1 to -10, and light to moderate W'ly ridge winds are expected today. Sat will be similar with up to 4cm of snow. Intense snowfall is expected on Sun with strong W'ly winds; avalanche danger will increase. On Mon, temps will begin to drop as arctic air moves in.
Snowpack Summary
Light snow overnight has covered a new surface hoar layer, steep solar aspects a sun crust, and ~10-20cm of surface facets in most areas. These layers will be worth watching if we get lots of snow over the weekend. The Nov 12 surface hoar layer is down 40-100cm, produced very large avalanches during the last storm, and still lurks in many areas.
Avalanche Summary
No new natural avalanches were observed yesterday. The Avalanche Control Section conducted a start of season shoot yesterday, sighting in the howitzers on two targets. Macdonald gully 10 produced a size 1.5 which ran into the fan, and Crossover produced a size 2.5 which stopped in the path.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.