An unusual weak layer makes steep and convex terrain features particularly dangerous.
Summary
Confidence
High -
Weather Forecast
TUESDAY NIGHT: Some flurries, but clearing after midnight.WEDNESDAY: Dry with sunny breaks. Freezing level rising to around 1000 m in the afternoon. Light northeasterly winds.THURSDAY: Dry and sunny. Freezing level around 700 m. Light northeasterly winds.FRIDAY: 10-15 cm new snow expected. Freezing level around 500 m. Moderate to strong southwesterly winds.
Avalanche Summary
On Monday, search and rescue responded to an avalanche in the Mount Seymour backcountry. The avalanche occurred on a steep feature at treeline elevation
(see photo here). Avalanche professionals involved in the rescue indicated wide propagation consistent with a persistent slab problem. The crown depth was variable - 40 to 100 cm, indicating there was wind loading in that area.On Friday and over the weekend, there is evidence of a widespread avalanche cycle up to size 2.5. These avalanches showed impressive propagation, with some being triggered remotely (from a distance) and some occasions stepping down to a 50 cm deep crust layer.
Snowpack Summary
30-50 cm of recent storm snow lies above a crust. The new snow has bonded poorly to this crust and natural and human-triggered avalanche have been noted on this interface. The reactivity of this layer appears to be worse in the south of the region (i.e. the North Shore Mountains) that have seen more snow. Unusually for this region, we expect this layer to remain reactive for some time into the future. New sun crusts may be found near the surface of south-facing aspects, while wind slabs may be found in exposed terrain. The lower snowpack is settled and strong.
jfloyer,
Avalanche Canada
