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.
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.
Localized areas may accumulate upwards of 25 cm in 24 hrs by 4 pm Friday. Expect new snow to be most reactive where impacted by wind. Fresh slabs may trigger other instabilities deeper in the snowpack.
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 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.
New snow continues to gradually accumulate. 5-15 cm recent snow covers a layer of surface hoar around treeline and higher, and a crust on steep solar aspects. A thick rain crust is now buried 10-40 cm up to 1700 m around Revelstoke and increasing to 2000 m travelling south through the region.
Two persistent weak layers in the middle of the snowpack may remain reactive to human triggering. They are both surface hoar layers that formed in early January and are typically found 40-90 cm deep throughout the region. There are also some deeper facet and surface hoar layers that formed in December, but recent snowpack observations suggest they are strengthening.
The bottom of the snowpack is made up of large weak facets buried in late November, which has caused a deep persistent slab problem for this region.
Upslope conditions Thursday night into Friday may produce larger snowfall accumulations on the eastern slopes of the Monashees. Isolated hot spots around Monashee Pass and between Shuswap Lake to Lake Revelstoke could accumulate upwards of 25 cm by 4 pm Friday.
Thursday night
Cloudy with isolated flurries, 5-10 cm. Ridge wind northwest 10-20 km/hr. Alpine low temperature -8 C. Freezing level dropping to valley bottom.
Friday
Scattered flurries, 5-15 cm. Ridge wind north 10-30 km/hr. Alpine temperature -8 C. Freezing level valley bottom.
SaturdayIsolated flurries clearing into blue skies. Ridge wind northeast 10-20 km/hr. Alpine temperature -15 C.
SundaySunny. Ridge wind northeast 5-15 km/hr. Alpine temperature -20 C.
More details can be found in the Mountain Weather Forecast.
