Regions
South Coast Inland.
Danger will increase towards the north. Little change is expected for the Coquihalla area, but northern areas are expecting up to 20 cm of new snow falling on a weaker snowpack.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
SUNDAY: Scattered flurries with 5-10 cm in the south and 10-20 cm in the north, strong southwest winds, freezing levels dropping to 1200 m.MONDAY: Cloudy with sunny periods, light west winds with moderate gusts, freezing levels dropping with alpine temperatures around -3 C in the south and -7 C in the north.TUESDAY: Isolated flurries with trace accumulations, light north winds, alpine temperatures around -8 C.
Avalanche Summary
On Friday, two skiers were caught in a size 2 wind slab avalanche that carried them down a steep north facing couloir in the Coquihalla area. Old wind slabs are likely lingering in immediate lee terrain, and new wind slabs will likely form on Sunday. Larger wind slabs are expected in the northern areas around Duffey Lake and the South Chilcotins, where there are greater amounts of snow in the forecast and widespread surface hoar on the surface.
Snowpack Summary
SOUTHERN AREAS (e.g. Coquihalla): Light flurries will bury a variety of crusts and settled storm snow with isolated wind slabs lingering on northerly aspects.NORTHERN AREAS (e.g. Duffey Lake): Moderate flurries will bury a hard surface composed of settled storm snow, crusts, and surface hoar. Strong southwest winds will form fresh wind slabs. The upper snowpack has 50-80 cm of settled storm snow sitting above the mid-January surface hoar and facet interface. This interface produced large avalanches during the last storm cycle, and may still be poorly bonded in thin snowpack areas such as the South Chilcotins.
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.