Avalanche Forecast

On Saturday a serious avalanche, presumed to have resulted in a fatality, occurred in the Oasis riding area south of Valemont. The avalanche was on a north-northeast aspect at 2100 m. It was remotely triggered and likely 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.

Flurries 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.

Overnight 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.

• Be mindful that deep instabilities are still present and have produced recent large avalanches.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
• Recent wind has varied in direction so watch for wind slabs on all aspects.