Regions
Northwest Coastal.
Significant accumulations of new snow will remain touchy, particularly in wind drifted areas, or in sheltered areas where it overlies a weak snowpack layer.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
THURSDAY: Light snow 5-10 cm, winds around 40 km/h from the southeast. Treeline temperatures around -7C.FRIDAY: Mix of sun and cloud, 40-60 km/h northwest winds, temperatures around -8C in the south of the region, colder further north.SATURDAY: An overnight storm may put up to 10 cm on the ground for Saturday morning, then clearing with 40-60 km/h northeast winds.
Avalanche Summary
An avalanche cycle was reported from the Terrace area during Monday and Tuesday's storm, although notably most of the avalanches appeared to be loose dry avalanches. Avalanches up to size 2.5 were also reported from the Ningunsaw area.
Snowpack Summary
Recent storms have deposited 50-80 cm new snow combined with strong, mainly southwest winds. Expect touchy wind slabs to have formed in the lee of exposed ridges. The storm snow has buried a layer of feathery surface hoar (up to 15 mm in sheltered areas), making wide propagations possible. A weak interface that formed during the early December cold snap can be found in isolated areas buried 100-150 cm deep. The layer consists of preserved surface hoar or weak faceted (sugary) snow. The lower snowpack is well consolidated in deep snowpack areas. In shallow snowpack areas, such as the northern part of the region, an old rain crust near the bottom of the snowpack has developed weak facets and might be triggerable from a thin or rocky area on a convex slope.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.