Snowfall should taper Tuesday night, but strong to extreme winds are expected to continue to produce natural avalanches in the alpine Wednesday. Seek out conservative terrain free of overhead hazard.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A series of pacific frontal systems are taking aim at BC this week, the Cariboos are poised to receive significant snow and wind. TUESDAY NIGHT: Freezing level around valley bottom, moderate south/southwest wind at treeline, strong to extreme southwest wind in the alpine switching to northwest around midnight, 2 to 5 cm of snow.WEDNESDAY: Scattered cloud cover in the morning, increasing cloud cover through the day, freezing level near valley bottom, strong west/southwest wind at treeline, extreme northwest wind in the alpine, 1 to 5 cm of snow during the day, 2 to 15 cm Wednesday night. THURSDAY: Overcast, freezing level around 1500 m, moderate to strong southwest wind at treeline, strong to extreme westerly wind in the alpine, 1 to 4 cm of snow.FRIDAY: Broken cloud cover, freezing level beginning around 1500 m potentially rising has high as 2000 m, strong southerly wind at treeline, extreme southwest wind in the alpine, trace of precipitation possible.
Avalanche Summary
Fresh wind slab formation was reported on Saturday and Sunday,
there is a great MIN report here. No other recent avalanche activity has been reported.
Snowpack Summary
As of Tuesday afternoon the storm has produced 10 to 25 cm of storm snow and another 5 to 10 cm are expected overnight. This new snow lies on the December 9th weak layer which consists of facets, surface hoar, and a crust on solar aspects. By Tues morning there could be 30 cm of settled storm snow with deeper wind slabs in lee alpine features. A buried weak layer exists 20 to 60 cm below the surface, it consists of a sun crust on steep south facing slopes and/or weak surface hoar crystals on more shaded and sheltered slopes. Although it is slowly healing, it may still react to triggers where surface hoar is sitting on the crust which is most prevalent on steep south facing terrain at treeline.At the base of the snowpack is a crust that formed in late October. The probability of triggering this layer is low, but the most suspect areas would be large, steep, rocky alpine features with a shallow snowpack. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer. Snowpack depths decrease dramatically with elevation.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.