Regions
Kootenay Boundary.
UPDATE: MONDAY DEC 17th @ 9amSignificantly more snow fell on Sunday night than was forecast. The combination of new snow, strong winds anda buried weak layer are a recipe for elevated danger ratings.
Confidence
Low - Due to the number of field observations
Weather Forecast
Monday will see lingering flurries before significant precipitation arrives on Tuesday.MONDAY: Cloudy with isolated flurries. Accumulation of 5-10 cm possible. Ridge wind moderate from the west. Temperature near -5. Freezing level 700 m.TUESDAY: Snow. Accumulation 20-35 cm. Ridge wind moderate from the southeast. Temperature near -7. Freezing level 500 m. WEDNESDAY: Clearing in the afternoon. Ridge wind moderate northerly. Freezing level at the surface.
Avalanche Summary
Early Monday morning we had reports small Size 1 storm slab avalanches being triggered off small features. A more widespread avalanche cycle is expected on Monday with significant wind-deposited snow amounts sitting on a weak surface hoar layer in many locations.
Snowpack Summary
UPDATE: MONDAY DECEMBER 17th @ 9am:Some areas saw 20-30 cm of new snow in Sunday night's storm, with moderate to strong winds. Snow drifts as deep as 60cm have been reported. This new snow has fallen on a variety of old snow surfaces, depending on aspect and elevation. On solar aspects a thin melt-freeze crust has been buried. On northerly aspects, feathery, surface hoar crystals (10-60 mm in length) have been buried below treeline as well as protected areas at treeline. In the alpine the old surface consisted of sugary snow (facets) and hard, wind scoured snow. Below the snow surface the upper snowpack is well settled and overlies a series of late-November crusts, now buried 20-50 cm and 15-25 cm thick. Recent snowpack tests have produced hard, resistant compression test results within the layers of this crust. Below the crust layer the lower snowpack is moist and well settled.
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.