A fatal avalanche incident occurred south of Valemont on Saturday. Reports of human triggered avalanches indicate the snowpack is very unstable in the region. Stick to well ridden and/or simple terrain.
Strong to extreme westerly wind will transport snow and form touchy wind slabs in alpine and treeline terrain. Be aware that wind slabs could step down to deeper layers.
A reactive surface hoar layer is found 40 to 70 cm deep throughout the region. Be especially cautious around steep convex openings at treeline and below. Remote triggering is also a concern for this layer.
A layer of large and weak facets sits near the base of the snowpack. This layer has most recently been problematic in upper treeline/lower alpine elevations.
Avoid thin and rocky start zones where weak layers sit closer to the surface, 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.
Remote triggering is a concern for this layer, avoid travelling below steep slopes.
On Saturday a serious avalanche, which resulted in a fatality, occurred in the Oasis riding area south of Valemont. The avalanche was on a north-northwest aspect at 2100 m. It was remotely triggered and ran on the November facets near the bottom of the snowpack. This large avalanche (size 2.5) had a depth of 80 to 120 cm. There were several other reports of human-triggered avalanches from nearby areas.
Over the past week, there have been numerous reports of large human-triggered avalanches on both a 50 cm deep surface hoar layer in the middle of the snowpack and weak facets at the bottom of the snowpack. See photos of some of these avalanches here and here. A very large deep persistent slab avalanche (size 3) occurred naturally in alpine terrain in the western Cariboos on Jan 18.
All of these very large avalanches occurred at upper treeline/lower alpine. Avalanches like these are most likely to be triggered on steep, shallow and previously undisturbed slopes.
New snow continues to gradually accumulate, with 5 to 15 cm of new snow expected each day this week. Westerly winds will continue to affect exposed terrain and form wind slabs near ridgetops. By Monday, 20 to 50 cm of recent snowfall could sit above a layer of surface hoar as well as a sun crust on steep solar aspects. Below 1600 m, recent snow is accumulating above a rain crust.
A prominent layer of buried surface hoar can be found roughly 40 to 70 cm deep. It has shown ongoing signs of instability in the Valemount area, and could potentially be problematic throughout the Cariboos and Northern Monashees. The bottom of the snowpack is made up of large weak facets buried in late November, which has caused a deep persistent slab problem across much of interior BC.
Monday night
Periods of snow with 5 to 10 cm, 40 km/h southwest wind, treeline temperatures cool to -12 °C.
Tuesday
Mostly cloudy with lingering flurries brining another 1 to 5 cm of snow, 50 to 70 km/h west wind, treeline temperatures warm to -8 °C.
TuesdayFlurries bring 5 to 15 cm of new snow by the morning then gradual clearing with some sunny breaks in the afternoon, 30 km/h northwest wind, treeline temperatures around -6 °C.
WednesdayOvernight flurries bring another 5 to 15 cm of snow by the morning then gradual clearing with some sunny breaks in the afternoon, 30 km/h northwest wind, treeline temperatures around -3 °C.
More details can be found in the Mountain Weather Forecast.
