North Columbia

Snow and wind beginning on Friday will add to existing slabs and grow cornices at upper elevations. Sloughing and cracking around skis and sleds are signs that the new snow is bonding poorly to the old surface. More snow is expected for Sunday.

Moderate - Forecast snowfall amounts are uncertain

FRIDAY: Flurries. Accumulation 5-10 cm. Ridge wind light, southwest. Temperature -12. Freezing level valley bottom.SATURDAY: Cloudy, light flurries. Accumulation trace. Ridge wind light, west. Temperature -10. Freezing level valley bottom.SUNDAY: Snow. Accumulation 10-15 cm. Ridge wind moderate, west. Temperature -6. Freezing level 500 m.

On Wednesday there were reports of several skier triggered slab avalanches up to size 2 (20-30 cm deep) on steep, southeast to southwest-facing features between 1900-2000 m, as well as explosive control results up to size 2.Tuesday there were several reports of skier triggered wind slab avalanches up to size 1.5 on a variety of aspects between 1800-2100 m, including a remotely triggered (from a distance) pocket of hard wind slab near ridge top. On Monday, several natural wind slab avalanches to size 2.5 were reported on a south / west through north / west aspects between 1800m and 2400m.On Sunday, natural wind slab activity was widespread above 1900m on primarily south east through west aspects. We received reports of an initial wind slab (size 2) stepping down to deeper weak layers and triggering a size 3.5 persistent slab, on a south west aspect near 2300m. Although deeper, persistent avalanche activity has become less frequent over the past week, light triggers in shallow rocky areas, as well as large triggers such as a cornice collapse or step down from a wind slab release, still have the potential to result in large destructive avalanches.

40-60 cm of recent storm snow is settling into a slab in the upper snowpack. Strong winds, most recently from the north, have redistributed these accumulations into stiff wind slabs in wind-exposed terrain. The recent snow sits on the old interface the was buried mid February consisting of; a mix of older wind slabs in exposed higher elevation terrain, a sun crust on steep solar aspects, a rain crust below 1600m, and surface hoar on sheltered slopes.Below the snow surface, several persistent weak layers make up a complex snowpack which is slowly beginning to show signs of improving but still remains suspect. In the top 150-200 cm of the snowpack, two surface hoar layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (200-250 cm) is a facet/crust/surface hoar layer from December, most prevalent at and below tree line.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.