Regions
South Coast Inland.
Danger will increase late on Thursday and into Friday as new snow accumulates.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Thursday
Weather Forecast
THURSDAY: Flurries increasing throughout the day with up to 5 cm in the north and up to 10 cm in the south, moderate south wind, freezing level rising to around 1500 m.FRIDAY: Another 10-20 cm of snow and then clearing in the afternoon, light wind, freezing level dropping to around 1000 m.SATURDAY: Mostly sunny with freezing level rising to around 1600 m.
Avalanche Summary
Numerous loose wet avalanches were observed in steep south-facing terrain on Wednesday and Tuesday. Most were small (size 1), but a few in the Coquihalla reached size 2.Last weekend, a few size 2 natural slab avalanches were reported in the northern part of the region on a range of aspects around 2000 m.
Snowpack Summary
New snow will accumulate on Thursday and Friday and form extra deep deposits in wind loaded terrain. The new snow is falling on a sun crust on steep south-facing slopes, cold dry snow on polar aspects, and wind affected snow at upper elevations.In northern parts of the region the mid-February weak layer is about 40 cm below the surface and has been reactive in some snowpack tests. The layer is composed of sugary facets, a sun crust on solar aspects, and surface hoar that is present at and below treeline. No recent avalanche activity has been reported on these layers.The snowpack is well settled in southern parts of the region (e.g. Coquihalla and Manning Park).Variable winds in the past month have created cornices on many alpine ridgelines. They will become touchier as they grow in size, as temperatures rise, and as the strong late-winter sun shines down upon them on clear days.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.