Make conservative decisions with the temperatures in mind, pay attention to the daylight and leave plenty of time to get home safely.
Wind slabs may be found on a variety of aspects as shifting winds have likely resulted in atypical reverse loading and cross loading patterns. Expect wind loaded pockets in lee terrain features such as just below ridge crests and roll-overs. Watch for drifted or stiffer areas of snow, or cracking under your skis.
A layer of weak facets (sugary snow) can be found down 80-150 cm near a crust layer that formed in early December. A skier triggered 2.5 was reported to have run on this layer on Sunday near Revelstoke.
The best strategy with a persistent avalanche problem is conservative terrain management - avoid likely trigger spots such as steep convex slopes, and areas where the snowpack tapers rapidly from thick to thin. Learn more about this problem here in a recent forecaster blog.
Arctic air maintains cold and clear conditions across the Columbias.
Monday night: Partly cloudy. No significant precipitation. Light southwest wind at 2000m, moderate northwest upper level winds. Alpine temperatures around -25 C.
Tuesday Partly cloudy with isolated flurries. Light southwest wind at 2000m, moderate northwest upper level winds. Alpine high -24 C.
Wednesday: Partly cloudy. Light southwest wind at 2000m, strong northwest upper level winds. Alpine high -25 C.
Thursday: Flurries bringing around 5 cm overnight then clearing. Light southwest wind at 2000m, moderate northwest upper level winds. Alpine high of -22 C.
Natural and human triggered wind slabs up to size 1.5 have been reported over the last few days.
The persistent slab problem continues to produce sporadic events on the early December crust/facet layer. A skier triggered size 2.5 was reported in the Monashees near Revelstoke on Sunday. This avalanche problem is challenging to forecast and is best managed by conservative terrain management.
If you head into the mountains, please submit your findings and photos to the Mountain Information Network!
40-60 cm of fresh storm snow has accumulated over the past week. In the alpine and exposed treeline elevations it has been redistributed into deeper deposits in wind loaded features. In the southern parts of the region, winds have been consistent from the southwest. In the north, southwest winds came in with the snow and were followed by a northerly blast, resulting in atypical loading patterns and wind slabs on all aspects.
At lower elevations the settling storm snow may sit over a weak surface hoar layer, which is creating slabs that are reactive to human triggers. The surface hoar is most likely to be found on sheltered slopes at treeline and below.
The crust formed by the early December rain event sits 100-150cm deep and is found up to 2200m in the North Columbias. In areas where the crust is buried deeper than one meter, it has begun to decompose and shows limited reactivity. In many areas, the snow above is well bonded to the crust. However in some areas around treeline and below, weak faceted grains have been observed above this crust - creating a weak interface that has proven to remain reactive to human triggers.
