Confidence
Fair - Due to variable weather conditions
Weather Forecast
Friday: mix of sun and cloud and very light flurries / moderate northwest winds / freezing level at 600m Saturday: increasing cloud in the afternoon with snowfall developing later in the day / winds increasing to strong and southwest by the end of the day / freezing level at 700m Sunday: moderate snowfall / moderate southwest winds / freezing level climbing to 1100m
Avalanche Summary
A size 2.5 natural was observed on an alpine feature in the Duffey Lake area on Wednesday. In the Coquihalla area, widespread windslab avalanches to size 3 were reported on Thursday
Snowpack Summary
On wednesday night another 25-30cm of snow fell with moderate southwest winds adding to the 50cm of snow that fell with strong southwest winds earlier in the week. Add all of this to the 25-40cms that fell over last weekend that now sits on top of the previous cold, low density snow from the last week and you've got a great recipe for deep storm and wind slab development. In general, snowfall amounts have been greatest in the Coquihalla area over the past week with total snowpack depths at treeline amounting to 390cm. In the Duffey Lake area, treeline depths are closer to 220cm.Persistent weak layers lower down in the snowpack have generally ceased to be of concern, except perhaps in very isolated, thin rocky 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.
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.
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.