South Columbia

As stormy weather tapers-off and a dry ridge gradually builds over the province, solar radiation will become the driver for natural avalanche activity.

Moderate - Timing or intensity of solar radiation is uncertain on Wednesday

On Tuesday night and Wednesday morning, expect a mix of sun and cloud with isolated spring "power flurries". Clouds should scatter by mid-day on Wednesday while Thursday and Friday will be mainly clear. Ridgetop winds will be light to moderate from the northwest on Wednesday, becoming generally calm on Thursday and Friday. Daytime freezing levels should sit at about 1200m for the forecast period.

On Monday, several wind slabs to size 2 were ski cut on a variety of aspects at treeline and in the alpine. The avalanches formed in response to new snow and wind on Sunday night. Explosives control also triggered older storm slabs including a size 3 avalanche on a southeast facing alpine slope. Persistent slab avalanches continue to fail on the late February weak layer. A sledder was killed on Sunday in a size 2 slab avalanche in the Monashees just north of Shuswap Lake. The avalanche occurred on a west facing convex roll at 1830m. The slab was 40-80cm deep, 60m wide and 65m long. The subject was found after more than an hour of probing as rescuers were not able to obtain a transceiver signal. Although this avalanche occurred only a few kilometers north of the regional boundary in the North Columbia region, similar conditions exist in the South Columbias. This was indicated by another avalanche in the southeast corner of the region (see the Mountain Information Network post near Kokanee Glacier). The avalanche, which resulted in a partial burial, was remotely triggered and was in the size 2 range.

On Monday up to 18cm of new snow fell. Moderate to strong southerly winds have shifted the snow into wind slabs in leeward terrain at treeline and in the alpine while intermittent sunny skies have likely promoted a melt-freeze cycle on some sun-exposed slopes. 60-110cm below the surface you'll find a persistent weak layer comprised of surface hoar, facets and/or a thick crust. This layer, which was buried on February 27th, seems variably reactive. In other words, it's still touchy in some places while in other places it's really tough to trigger, and there's not much of a reliable pattern telling us what exact aspects are most suspect. I'd continue to be suspicious of steep, unsupported features at treeline and in the alpine as this layer has the potential for very large avalanches. Below this interface, the snowpack is generally gaining strength. At ridgetop, cornices are huge and could be become increasingly touchy with forecast solar radiation.