South Columbia

Storm slabs continue to be reactive to human-triggering and large avalanches are still a major concern. Use a conservative approach to travel and stick to mellow terrain until conditions improve.

Fair - Timing, track, or intensity of incoming weather system is uncertain

Unsettled spring conditions are expected on Tuesday. A mix of sun and cloud is forecast with localized convective snow flurries. Freezing levels are expected to reach around 1700m with light alpine winds. Good overnight recovery is expected with freezing levels falling to near valley bottom Tuesday overnight. On Wednesday, a warm storm system on the coast spills into the interior bringing light precipitation in the afternoon. Models are currently showing 4-8mm between Wednesday afternoon and Thursday afternoon. On Wednesday, freezing levels are expected to reach around 1800m and alpine winds are expected to become moderate from the SW. On Thursday, freezing levels are forecast to reach around 2500m by the end of the day.

A widespread natural avalanche cycle occurred on Saturday with storm slabs up to size 3 being reported. These avalanches were typically failing 40-60cm deep but were over 1m deep in wind loaded areas. At lower elevations, these slabs were moist or wet. On Sunday, natural avalanches tapered off but were still occurring on sun-exposed slopes. Many explosive and human-triggered storm slab avalanches were also reported on Sunday. There were several remotely triggered avalanches with the farthest being triggered from 100m away. One cornice triggered slab avalanche is expected to have stepped down to a deep weak layer from January. On Tuesday, human-triggered storm slab avalanches remain a concern, especially in steep alpine terrain.

At higher elevations, 40-60cm of dense storm snow sits over the mid-March interface which had included crusts, moist snow, wind affected surfaces, and/or old wind slabs. New snowfall amounts taper off towards the south of the region. In exposed terrain, strong SW winds had redistributed the new snow into wind slabs on leeward features. Down 50-80cm is the mid-February facet/crust interface. This interface appears to be well bonded in the South Columbia region but in the North Columbia region it is very reactive and has produced numerous large avalanches. There is still some concern for this layer to wake-up in the South Columbia region and storm slab avalanches have the potential to step down to it. On Sunday, the snow surface was reported to be wet to around 1700m and moist to around 2000m (higher on solar aspects). The snow surface is now expected to be undergoing melt-freeze cycles as freezing levels drop overnight.