South Coast Inland

Storm and wind slabs are only half of the picture on Saturday. Persistent weaknesses deeper in the snowpack have given recent feedback that can't be ignored.

Moderate -

Saturday: Cloudy with scattered flurries bringing 5-10 cm of new snow. Moderate to strong southwest winds. Freezing level to 1500 metres with alpine temperatures of around -2. Sunday: Cloudy with scattered flurries and a trace to 5 cm of new snow. Moderate to strong southwest winds. Freezing level to 1600 metres with alpine temperatures of around -2. Monday: Cloudy with scattered flurries and approximately 5 cm of new snow. Moderate to strong southwest winds. Freezing level to 2000 metres with alpine temperatures of around 0.

Reports from Thursday included one explosives triggered Size 3 avalanche in the Duffey Lake area that began as a shallow surface slab before stepping down to one of our February weak layers. A social media report from the same area details a remotely triggered Size 2 storm slab on a southeast aspect near treeline. A recent MIN report from the Temple Valley area describes a Size 3 avalanche which occurred on Wednesday and was apparently cornice triggered. Further reports from Wednesday include observations of several 24-36 hour old natural storm and wind slab avalanches that had released from Size 1.5-2.5 on southeast to southwest aspects at treeline and above in the north of the region. Crown fractures averaged 40-70 cm but reached as deep as 120 cm. Looking forward, recent persistent slab avalanche activity support ongoing concern for large avalanches releasing on our February weak layers. While natural avalanches on these layers may become unlikely, evidence suggests a lingering possibility for a rider to directly trigger a persistent slab or for a smaller avalanche to 'step down'.

Another 15-25 cm of new snow over Thursday night has brought typical storm accumulations from the past week to 70-105 cm in the north of the region and to well over a metre in the south of the region. Recent and ongoing south to southwest winds have redistributed much of this snow in wind-exposed terrain, forming touchy wind and storm slabs. The above mentioned storm snow overlies the mid-February and late-February interfaces, which may be close together in the snowpack. The late-February interface consists of wind affected surfaces in exposed terrain, sun crust on steep solar aspects, and facets and surface hoar in sheltered areas. The mid-February interface consists of a thick rain crust which extends to at least treeline, a sun crust on steep solar aspects, and in many places, a layer of facets overlying the crust. Recent observations suggest the late-February layer is most reactive in the north of region while the mid-February layer is most reactive in the south of the region. Below these layers, the mid and lower snowpack are generally well settled and strong.