There is a lot of uncertainty with the reactivity of deeply buried weak layers. Conditions like this are best managed by sticking to lower-angle terrain away from any overhead hazard.
10-30 cm in the last few days leaves plenty of snow for ongoing wind slab development. Arctic outflow may reverse-load features and build slabs in less common areas.
Numerous problematic weak layers exist in the top meter of the snowpack, with recent observations suggesting the most likely of these to trigger are surface hoar layers found 40-90 cm deep. Be especially cautious around steep convex openings at treeline and below.
A layer of large and weak facets sits near the base of the snowpack. This layer has been most problematic in upper treeline/lower alpine elevations. Riders are most likely to trigger an avalanche on this layer in steep, shallow previously undisturbed terrain or by first triggering a layer further up in the snowpack.
On Thursday, wind slab avalanches up to size 2, occurring on all aspects above 2000 m were reported. Explosives triggered a size 3 avalanche on the Deep Persistent facets, and a couple of natural Deep Persistent slab avalanches were reported between 2000-2500 m.
On Monday, a fatal skier-triggered avalanche incident occurred in the Selkirk range near Revelstoke. The avalanche was on an east aspect at 1900 m. It occurred on a steep, unsupported open slope below treeline and failed on a weak layer of surface hoar buried in early January. This was a size 2 with a crown depth of 50 cm.
Numerous natural and human-triggered wind slabs were also observed on Sunday through Tuesday throughout the region, ranging in size from 1.5-2.5. One of these avalanches in the south of the region resulted in a partial burial. These avalanches mainly occurred on east and northeast aspects in the alpine and treeline.
High-consequence avalanche activity has been ongoing for several weeks. Your best defence is to stay diligent in choosing low-consequence terrain. Stick to slopes that have been heavily trafficked throughout the winter and avoid venturing into untouched zones. Stay disciplined and adjust your expectation for this winter.
Surface snow varies by elevation with recent warm temperatures turning snow moist up to 1800 m and now heading into a cooling trend. 10-35 cm of recent snow covers a layer of surface hoar and thin crust on steep solar aspects around treeline and higher, and a thick crust up to 1700 m around Revelstoke and increasing to 2000 m travelling south through the region.
Two layers of surface hoar which formed in early January are found 40-90 cm deep, these persistent weak layers have recently been reactive to human triggering. Deeper in the snowpack are two surface hoar/facet layers that were active earlier in the season, but recent snowpack observations suggest they are strengthening. The bottom of the snowpack is made up of large weak facets buried in late November, causing the Deep Persistent Slab problem for this region.
Friday night
Scattered flurries as cold arctic air moves south. Most areas trace to 5 cm, and isolated areas of the southern Selkirks could see up to 15 cm. Ridge wind north 10-20 km/hr. Alpine temperature -14 C.
Saturday
Layered cloud with sunny breaks. Ridge wind northeast 15-30 km/hr. Alpine temperature -16 C.
SundaySunny. Ridge wind northwest 10-20 km/hr. Alpine temperature -20 C.
MondaySunny. Ridge wind northeast 5-15 km/hr. Alpine temperature -20 C.
More details can be found in the Mountain Weather Forecast.
