Human triggered avalanches are possible on steep slopes at higher elevations. Be extra cautious in wind-affected terrain.
A weak frontal system will form new wind slabs on north and east aspects, while old stubborn buried slabs may exist on all aspects in steep high elevation terrain.
A weak front crosses the region on Friday night.
FRIDAY NIGHT: Cloudy with some scattered flurries and 5-15 cm of new snow, strong southwest wind, freezing level drops to valley bottom with treeline temperatures dropping to -8 C.
SATURDAY: Cloudy with some isolated flurries, light southwest wind, freezing level around 1400 m with treeline temperatures around -5 C.
SUNDAY: Cloudy with some scattered flurries, light south wind, freezing level around 1200 m with treeline temperatures near -5 C.
MONDAY: 5-10 cm of new snow by the morning then clear skies in the afternoon, light wind, treeline temperatures around -5 C.
On Thursday there was a fatal avalanche between New Denver and Kaslo where a snowmobiler triggered a size 3 persistent slab avalanche on a west aspect at 2400 m. The avalanche likely failed on the late January weak layer (see the Incident Report here). This avalanche problem has become much less reactive since then, as recent weather has helped stabilize the snowpack
Warm sunny weather between Wednesday and Friday resulted in a widespread cycle of wet loose avalanches on sun-exposed slopes. These were mostly small (size 1-1.5), but a few large (size 2.5) wet avalanches were also reported. Heating also caused some cornice falls, ice falls, and small wind slab avalanches.
The primary concern this weekend will be wind slabs, both old ones lingering on all aspects and new ones forming on north and east facing slopes. A notable human triggered avalanche from Wednesday provides a good example of the old wind slab problem, as a skier triggered a size 3 avalanche in a steep south-facing couloir in Glacier National Park (MIN report).
10-15 cm of new snow will accumulate above moist and crusty interfaces that formed during the recent warm up. Some deeper accumulations can be expected in lee terrain features. High shaded terrain will have a mix of soft snow and some old buried wind slabs. The lower snowpack has strengthened over the past week as previous persistent weak layers have become mostly unreactive. The main layers that we had been tracking are a layer of facets that was buried in mid-February (50-100 cm deep) and a layer of surface hoar and/or crusts that was buried in late January (80-120 cm deep).
