South Coast

Stormy weather is coming, and avalanche danger will increase with wet and windy conditions.

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Light snow overnight with moderate southwest winds and freezing levels around 500 metres. Light snow continuing on Thursday with increasing southwest winds and freezing levels rising up to about 900 metres. Light snow Friday morning becoming heavy snow/rain in the afternoon as strong southerly winds push warm and wet air into the region causing freezing levels to rise up to at least 1700 metres. Heavy snow and strong winds continuing overnight into Saturday morning. 

On Tuesday a skier remotely triggered a size 3.0 slab avalanche from 20 metres away that released on the early January surface hoar. This avalanche happened at 2300 metres on a south-southeast aspect in the Duffey Lake area. The fracture propagated 350 metres and ran 750 metres to the valley bottom. Reports from Monday include evidence of natural avalanche activity on Sunday in the Duffy Lake area with observations of several recent storm slab avalanches up to Size 2. On Sunday, there was a report of a size 2 wind slab avalanche that was remotely triggered by a skier in the mountains north of Pemberton. It was triggered from a thin snowpack area and released on a steep cross-loaded slope about 50 m away. Nearby, a cornice fall also triggered a size 1.5 slab on the wind-loaded slope below.

In the south, 40-70 cm of recent storm snow sits on a widespread and generally supportive rain crust that was buried on Jan. 28. The bond to the crust appears to be fairly good but at least one notable storm snow weakness was observed 10 cm above the crust. Fresh pockets of wind slab may also form in immediate lee features. The combination of heavy storm loading, rain, and warm temperatures likely flushed out the mid-January persistent weakness in most areas in the Cascades. Further north, generally 20-40 cm of dry storm snow overlies the late-Jan rain crust below around 1800-2000 m. Above this elevation the new snow sits on settled storm snow or previously wind affected surfaces. Fresh pockets of wind slab are likely in exposed lee terrain. Where it still exists, the mid-January surface hoar layer is between 60 and 130 cm below the surface. This persistent weakness could be lingering on higher elevation slopes that did not previously avalanche and triggering remains a concern.