Northwest Coastal

New storm slabs are developing above variable crusts that may change rapidly with elevation. Persistent slab problems continue to be a concern for large avalanches.

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

5-10 cm of snow overnight above 600 metres with moderate southwest winds. Saturday should be the coolest day in the forecast period with freezing levels remaining below 800 metres. 5-10 cm during the day with strong southwest winds. On Sunday the warm air moves in again with freezing levels rising up to about 1200 metres combined with strong southwest winds and 10-15 cm of snow in the alpine. Monday is expected to be the warmest and wettest day, precipitation amounts have dropped over the last few model runs, but expect 15-30 mm with strong winds and high freezing levels.

A widespread natural avalanche cycle up to size 3.5, as well as skier remotes in the alpine were reported from Thursday in the northeast of the region in the Bell-Irving area. Some of these avalanches stepped down to weak facetted snow near the ground. Explosives control on Thursday resulted in a size 2.5 slab avalanche that released on the persistent weak layer in the north of the region in the Ningunsaw area. On Wednesday, several loose wet slides were reported from the Shames backcountry that were visible in the Geronimo bowl. On Tuesday explosives control in the Bear Pass highway corridor produced slab avalanches in the alpine up to size 4.0 with wide fracture propagations. Reports of natural activity during the recent storm of slab avalanches up to size 4.0 releasing in the storm snow or on the deeply buried persistent weak layer from early January.

Temperatures have been gradually dropping and the freeze/crust line has been dropping as well. Breakable crusts have been reported as low as 1000m in the south of the region. In the Shames backcountry on Thursday, there was a supportive crust above 1300 metres that had developed overnight, on Wednesday there was no crust at 1300 metres ( the highest point the observer reached), and there was 50 cm of recent storm snow, with the top 25 cm being rain soaked. This moist and wet storm snow was sitting on the old crust from the previous warm storm at the end of January. Compression tests resulted in moderate shears within the storm snow and on the old crust. The January 9th surface hoar/facet layer is down 70-200 cm across the region and remains a concern for commercial operations. In the north of the region, we continue to get reports of natural and remotely triggered avalanches on the early January persistent weak layer, large avalanches have released where this layer steps down to weak basal facets. A very conservative approach to mountain travel is still required, due to another warm and wet storm system forecast over the next few days.