Northwest Coastal

Wind and light snowfall will continue to drive slab formation particularly on leeward and exposed slopes.  These slabs may be especially reactive in sheltered areas at and below treeline where surface hoar has been buried.

Moderate - Due to the number of field observations

TONIGHT: Flurries. Accumulation 5-10 cm. Ridge wind moderate, south. Temperature -6. Freezing level 800 m.WEDNESDAY: Flurries. Accumulation 5-10 cm. Ridge wind moderate, south. Temperature -3. Freezing level 500 m.THURSDAY: Mix of sun and cloud, light flurries. Accumulation trace. Ridge wind light, east. Temperature -4. Freezing level 200 m. FRIDAY: Flurries. Accumulation 5-10 cm. Ridge wind moderate, south. Temperature -5. Freezing level 300 m.

Monday areas north of Stewart reported numerous natural loose storm snow avalanches on most aspects, and one skier remote Size 1.5 storm slab avalanche on a southerly aspect at 1400 m and is suspected to have failed on the mid-December interface following a large whumpf.Reports from Saturday included one observation of a remotely (from a distance) triggered Size 1.5 storm slab releasing on a steep north-facing roll at 1100 m. This is suspected to have run on surface hoar buried beneath the recent snow accumulations.Last week natural, skier, and remote triggered storm slab avalanches to Size 2.5 were observed on most aspects and elevations. Also an older natural Size 2.5 persistent slab release was observed southwest of Rosswood. This slab was about 80 cm thick, failed on a low elevation moraine feature on a north aspect, and is suspected to have run on the weak layer from late December.

Approximately 40-60 cm of recent storm snow covers widespread temperature crusts as well as more isolated surface hoar at mid elevations that were buried mid-January. Areas where surface hoar has been recently buried are an increasing concern as the overlying storm snow gradually consolidates into a slab above it. This surface hoar is more likely to exist in sheltered areas at lower elevations. Professionals have been monitoring a few layers in the mid snowpack, including crusts and surface hoar layers that were buried early-January, late-December, and mid-December and can now be found 70-130 cm below the surface. Although these layers have been reactive in recent snowpack tests, only one recent report exists of a persistent slab releasing over the late-December weak layer. These layers are a greater concern in the north of the region. The lower snowpack is generally strong, with the exception of areas around Stewart and further north where a basal crust and facets exist.