Incremental snow and sustained wind will keep avalanche hazard elevated. Avoid freshly wind-drifted areas and continue to make conservative terrain choices while the storm snow gains strength.
Sustained southwest winds have a sufficient supply of snow to continue to drift into wind slabs on lee slopes at upper elevations. These wind slabs will likely be reactive to human triggering.
In the north of the region, a layer of weak facets (sugary snow) can be found near crust layers that formed in early December. It is possible that this facet-crust combination will react as a persistent slab problem with rapid loading from recent snow. This potential persistent slab problem warrants diligent, conservative route selection at treeline elevations. Avoid open slopes and convex rolls near treeline where weak layers may be preserved.
25-50 cm of recent storm snow has formed a widespread storm slab problem that may remain possible to human trigger. Closely monitor how the recent storm snow is settling and bonding to the old surface.
Saturday night: Cloudy, up to 10 cm of snow, strong southwest wind, treeline temperatures dropping to -8 C, freezing level at valley bottom.
Sunday: Mainly cloudy, up to 5 cm of snow, moderate southwest wind, treeline temperatures near -9 C, freezing level around 500 m.
Monday: Mainly cloudy, up to 5 cm of snow, moderate winds becoming east, treeline temperatures near -8 C, freezing level around 500 m.
Tuesday: Mix of sun and cloud, light variable winds, treeline temperatures near -10 C, freezing level at valley bottom.
Human-triggered avalanches remain likely on Sunday.
Early Saturday morning, operators reported a natural avalanche cycle releasing several large (up to size 2.5) and one very large (size 3-3.5) avalanches breaking within the storm snow.
Intense bands of precipitation are forecast to bring another 10-20 cm of snow to the mountains in a highly localized pattern. Sustained southwest winds will have a sufficient supply of snow to drift into reactive wind slabs at upper elevations. Avoid freshly wind-loaded terrain features on Sunday (for example, down-wind of ridges and roll-overs).
A powerful storm on Friday night brought strong southwest winds and 25-50 cm of new snow to the mountains, favoring areas in the south of the region. A gradual temperature rise during the storm created warmer denser snow over colder lighter snow, and in many locations, storm accumulations sit on crust layers that formed in early December. This tricky combination of slab and sliding surface may require more time to recover and gain strength and warrants careful evaluation and cautious routing-finding.
In the north of the region, the snowpack near upper treeline elevations is complex and warrants conservative route selection. Weak faceted snow can be found near two possible crust layers that formed in early December, which may become reactive with loading from new snow. Our models suggest that this layer may be most pronounced at elevations between 1400-1800 and in areas north in the region, like the Hurley.
The south of the region has seen substantially higher snow totals over the past week, with areas near the Coquilhalla seeing over a meter of accumulation since Monday. Expect to find deeper snow accumulations above the December crust and anticipate larger storm slab avalanches. Having endured warmer temperatures and more rainfall, the southern part of the region is just reaching the threshold for avalanches at most elevations.
