Regions
Northwest Inland.
In most areas, wind slabs are expected to be the primary concern on Monday. However, if your local area sees more than around 30 cm of new snow accumulate, a more widespread storm slab problem should be expected and the local hazard could be HIGH.
Confidence
Low - Intensity of incoming weather systems is uncertain
Weather Forecast
Snowfall is expected for Sunday overnight and Monday but weather models are varying substantially on amounts. Anywhere from 10-50 cm of snowfall is possible between Sunday evening and Monday evening. Alpine winds are expected to be extreme from the southwest overnight and strong from the west on Monday. Freezing levels are forecast to be around 700 m on Monday afternoon. Light snowfall is forecast to continue Monday overnight and Tuesday. Alpine wind should remain strong from the west and freezing levels should remain around 700 m. Another period of moderate snowfall and extreme alpine wind is currently forecast for Tuesday night and Wednesday.
Avalanche Summary
No recent avalanches have been reported in this region. Highly variable snowfall amounts will dictate the local avalanche danger and avalanche problems on Monday. In areas that receive less than around 30 cm of new snow, wind slabs will be the primary concern. In deeper snowfall areas, a more widespread storm slab problem may develop. The new snow sits over a weak interface which is expected to increase the reactivity of new slabs.
Snowpack Summary
The new storm snow sits over a highly variable interface resulting from over a week of clear skies, cold temperatures, and strong outflow winds. This mid-December interface consists of scoured surfaces and hard wind slabs in wind exposed terrain, widespread faceting of the upper snowpack, and surface hoar in sheltered areas. The new snow is expected to bond poorly to this interface.Snowpack observations have been very limited recently in the region. An old social media post near Smithers suggests there is a layer of surface hoar in the upper snowpack. The snowpack is very shallow throughout the region and widespread faceting of the entire snowpack is expected in most areas. A thick rain crust that formed in early November is probably near the bottom of the snowpack and is expected to be developing facets. Reports from the Ningunsaw Pass area and the far north of the region suggest that depth hoar is developing in shallow snowpack areas.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.