South Columbia

Storm slab avalanches are likely this weekend. The combination of fresh snow and clear skies will make the snow extra reactive on south-facing slopes.

High -

SATURDAY: Sunny with moderate west wind, freezing level up to 1200 m, and alpine high temperatures near -6 C.SUNDAY: Cloudy with flurries increasing throughout the day (10-20 cm of snow), moderate west wind, freezing level up to 1200 m, and alpine high temperatures near -6 C.MONDAY: Mostly cloudy with light wind, freezing level up to 1000 m, and alpine high temperatures near -8 C.

On Thursday, several size 1 skier triggered storm slab avalanches were reported. They were 30-50 cm thick and occurred on north and east aspects above treeline. One of the slabs subsequently triggered a larger size 2 avalanches that ran on the late-March crust. Some natural size 2-3 storm slabs avalanches were also reported in alpine terrain and a cornice fall in the Selkirks triggered a size 2.5 avalanche on an unidentified 2 m deep weak layer. On Tuesday and Wednesday, widespread natural avalanche activity was reported on all aspects in the alpine with size 1.5-3 storm slabs. These were predominantly failing on the recently buried late-March interface with crown depths of 30-40 cm and up to 100 cm in some areas. Several skier and remotely (from a distance) triggered avalanches up to size 2 were also reported in alpine terrain.

Another 15-30 cm of snow on Friday brings the weekly total to 40-80 cm, with amounts tapering with elevation.The storm snow sits on an interface buried in late-March that consist of crusts below 1900 m and on south aspects, and surface hoar on shaded aspects at higher elevations.Pockets of surface hoar (buried mid-March) have been reported on shaded aspects at higher elevations and may be found approximately 60-80 cm below the surface.Deeper persistent weak layers from January and December are still being reported by professional observers, but are generally considered dormant.