Regions
South Coast Inland.
Watch for wind slabs lingering at higher elevations. Thanks to everyone who's shared observations on the MIN last weekend!
Confidence
High - Due to the number and quality of field observations
Weather Forecast
TUESDAY: Mix of sun and cloud, moderate northeast winds, alpine temperatures around -12 C.WEDNESDAY: Sunny, moderate northeast winds, alpine temperatures around -12 C.THURSDAY: Sunny, light east winds, alpine temperatures around -14 C.
Avalanche Summary
Recent MIN reports do a great job highlighting recent avalanche activity in the region. Wind slabs were very reactive to human triggers over the weekend in northern parts of the region, releasing numerous size 1-1.5 avalanches on north and east aspects. Wind slabs may continue to be reactive to human triggers in the lee of exposed terrain at higher elevations. In thin rocky areas to the north, wind slabs could potentially step down to deeper weak layers.
Snowpack Summary
Sunday's storm delivered 10 cm of new snow. Strong southwest winds have left wind slabs lingering in the lee of exposed terrain. The new snow sits above a thin breakable sun crust and isolated pockets of surface hoar, potentially creating weak interfaces for wind slabs to propagate along. In southern areas (e.g. Coquihalla), the lower snowpack is well settled. In northern areas (e.g. Duffey Lake), the mid-January surface hoar and facet interface is now buried 50-80 cm deep. This interface produced large avalanches two weeks ago during the last major storm, 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.