North Columbia

Fresh storm slabs have formed over a snowpack that contains several deeply buried weak layers. Consider the avalanche danger to be HIGH around slopes that see direct sunshine on Monday.

Moderate -

Monday: Mainly cloudy with a greater chance of sun in the north of the region. Isolated flurries may bring a trace of new snow. Light northwest winds. Alpine high temperatures around -10.Tuesday: A mix of sun and cloud with cloud increasing and flurries beginning in the evening. Light west winds. Alpine high temperatures of -9.Wednesday: Cloudy with continuing flurries bringing 5-10 cm of new snow, increasing overnight. Light west winds. Alpine high temperatures of -4.

Reports from Saturday included observations of numerous natural storm slab releases from size 1.5-3 throughout the region. Activity was observed on all aspects and elevations, with higher elevations proving the most active. Several very large persistent slabs were observed to have run naturally throughout the north and south Columbias.Friday's reports showed new storm slabs becoming touchy and producing numerous natural, remotely triggered, and ski cut releases from size 1-2.5. Crown depths ranged from 10-30 cm deep. Two recent size 2.5 natural persistent slab avalanches that failed on the mid-December weak layer were observed at 1500-1700 metres in the north of the region.Explosive control on Wednesday and Thursday yielded numerous persistent slab results from size 2 to 3.5 on all aspects/elevations. All our persistent weak layers of concern were active. The mid-December layer is also suspected in two natural size 4 releases in and near the Glacier National Park area.On Tuesday, a size 2.5 avalanche on a northeast facing slope at 1920 m in the Clemina Creek area resulted in a single fatality. More details are available here.

Another round of snowfall began on Sunday morning and 15-20 cm of new snow is expected to accumulate on the surface by Monday. This is adding to 80-160 cm of recent storm snow which has settled into a slab (aided by recent wind and warming events) above the mid-January weak layer.Four active weak layers are now quite deep in our snowpack:1) 80 to 160 cm of storm snow sits on the crust and/or surface hoar layer from mid-January. The crust is reportedly widespread, with the possible exception of high elevation north aspects. The surface hoar is 5 to 20 mm in size and was reported at tree line elevations and possibly higher. 2) Deeper in the snowpack, the early-January persistent weak layer is 180 to 200 cm below the surface. It is composed of surface hoar on sheltered slopes as well as sun crust on steep solar aspects and is found at all elevation bands. 3) Another weak layer buried mid-December consisting of a facet/surface hoar/crust combination is buried 200 cm or more below the surface. It is most problematic at and below tree line. 4) A crust/facet layer from late November is yet another failure plane responsible for very large recent avalanches.