A problematic weak layer has surprised riders and triggered large avalanches.
Remote triggering is a concern, avoid exposure to steep overhead slopes.
Recent winds have varied in direction. Watch for wind slabs on all aspects and use caution as you enter wind-affected terrain.
Recent large avalanches have failed on weak grains over a buried crust. This weak layer has shown wide propagation across large terrain features.
Natural and rider-triggered wind slab avalanches to size 2 were reported over the past couple of days.
In the last week, very large (size 2-4) natural and human-triggered persistent slab avalanches have been reported. These avalanches have exhibited unexpectedly wide propagation, with some remote triggers occurring from distances up to one kilometre away.
On the 28th this near miss surprised riders, and this MIN describes avalanches triggered from valley bottom.
The alpine has seen extensive recent wind affect. Recent strong winds have varied in direction, building slabs on many aspects. Soft snow still exists in sheltered terrain and in the trees.
Our primary concern is a persistent weak layer of surface hoar and facets overlying a crust. It is buried 50 to 100 cm deep in the southern parts of the region and up to 200 cm deep in areas north of Stewart. Several recent large avalanches have failed on this layer producing wide propagation. Looking forward, we expect this layer to remain a concern for many days, or even weeks.
The remainder of the snowpack is well settled, with no deeper layers of concern. Treeline snow depths are around 160 cm.
Friday night
Cloudy. 10 to 20 km/h southwest ridgetop wind. Treeline temperature -14 °C.
Saturday
Cloudy with isolated flurries, trace to 10 cm snow. 25 to 45 km/h west ridgetop wind. Treeline temperature -12 °C.
Sunday
Mostly cloudy. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -10 °C.
Monday
Sunny. 20 to 40 km/h west ridgetop wind. Treeline temperature -8 °C.
More details can be found in the Mountain Weather Forecast.
