Avalanche Forecast

Fair - Timing or intensity of solar radiation is uncertain on Sunday

There are remnants of a system moving up from south of the border that may bring some moisture into the South Columbia mountains on Saturday night. Unsettled conditions are expected across the Interior regions again on Sunday. Some areas may see periods of heavy convective flurries, while others may see broken skies or scattered cloud. Winds should stay mostly light from the south, and the freezing level is expected to drop to the valley bottom Saturday night and then rise to about 800 metres on Sunday. Monday is forecast to be unsettled again, but with more likelihood of sunny periods. A Pacific frontal system is expected to start moving in from the coast on Tuesday bringing strong westerly winds and heavy precipitation.

Size 3.0-3.5 natural avalanches continue to be reported regularly from various aspects and elevations. Natural cornice falls up to size 3.0 are also occurring on a daily basis. Another natural size 4.0 avalanche was reported from the region on Thursday that may have released on a weak layer of basal facets, or scoured down to the ground once it was in motion.

Convective flurries brought about 5-10 cm to most parts of the region, some areas reported up to 20 cm of new snow and graupel. The recent series of storms have developed a storm slab that is about 100 cm thick, and reported to be settling and stiffening. The storm slab is sitting on a mix of old hard windslabs and crusts. There is a persistent weak layer (PWL) of buried surface hoar from mid-february that is buried between 100-200 cm that is the main concern. This PWL shears with a fracture character that promotes wide propagations that result in very large avalanches. Recent avalanches up to size 4.5 have exceeded historical avalanche paths and resulted in the demolition of old timber. Very large weak cornices have developed during the recent stormy period. Even brief sunny periods over the next few days may cause natural activity in the storm slab, which may propagate the deeper weak layers.