South Columbia

Touchy storm slabs will make for tricky conditions on Sunday. Conservative decision making is critical. Stick to low angle slopes and avoid steep avalanche terrain.

Fair - Due to the number of field observations

A weak ridge of high pressure should bring a mix of sun and cloud for Sunday. Freezing levels are forecast to reach around 1800m in the afternoon and alpine winds are expected to be light. Good overnight recovery is expected during the forecast period with freezing levels falling to around valley bottom each night. On Monday and Tuesday, mostly cloudy conditions are expected with scattered convective flurries. Afternoon freezing levels should reach around 1600m each day and alpine winds should remain light.

On Thursday and Friday, numerous storm slabs up to size 2 were reported. This were primarily human-triggered and typically above 2000m. Numerous natural loose wet avalanches up to 1.5 were also reported from lower elevations. With the additional loading on Saturday, natural storm slab avalanches are expected to be occurring. On Sunday, natural activity is expected to taper off as temperatures become cooler. However, if the sun is out in the afternoon, natural avalanches are possible from sun-exposed slopes. Human-triggering of storm slabs is expected to be a major concern for the next few days, especially at higher elevations where the snow is still dry.

At higher elevations, new storm snow (40-60cm) sits over a variety of surfaces including moist snow, crusts, wind affected surfaces, and/or old wind slabs. New snowfall amounts taper off substantially towards the south of the region. In exposed terrain, strong SW winds have redistributed new snow into wind slabs on leeward features. The snow surface has been reported to be wet to around 1700m and moist to 2300m. The snow surface is now expected to undergo melt-freeze cycles as freezing levels fluctuate overnight. Down 50-80 cm is the mid-February facet/crust interface. This interface has not been very reactive in the South Columbia region but in the North Columbia region it has produced numerous large avalanches. With the new storm loading, this layer may become reactive and storm slab avalanches have the potential to step down. The late-January crust/surface hoar layer (over 1m deep) and the mid-January surface hoar (around 1.5m deep) have been dormant for several weeks.