Northwest Coastal

A combination of sustained snowfall, extreme winds, and rising freezing levels is ramping up avalanche danger in the region this weekend.

High -

Saturday night: Periods of snow bringing approximately 15 cm of new snow. Extreme southwest winds.Sunday: Periods of snow delivering another 15-20 cm of new snow. Extreme southwest winds. Freezing level rising to 1000 metres with alpine temperatures around -1.Monday: Periods of snow and wet flurries bringing approximately 10 cm of new snow. Winds strong to extreme from the southwest. Freezing level rising to 1800 metres with alpine temperatures of +2.Tuesday: Periods of snow and wet flurries bringing 10-15 cm of new snow. Extreme south winds. Freezing level 1900 metres with alpine temperatures of +3.

Although the potential for avalanche activity is now rising quickly, few avalanches have been reported over the past few days. Friday's reports included some explosives control that met with limited success targeting wind slabs northeast of Terrace. Four out of eleven charges produced results up to Size 1.5.On Sunday, expect a transition from our previous wind slab problem to a more generalized and increasing storm slab problem as new snow accumulates and extreme winds promote rapid slab formation. Keep in mind that a basal weakness continues to drive a low probability/high consequence problem for shallow snowpack areas, especially in the north of the region.

New snow has begun to cover the widespread wind affected surfaces recently reported in exposed terrain. This includes scoured surfaces, sastrugi, and hard wind slabs. In areas sheltered from the wind, the surface snow now being buried was recently reported faceting with surface hoar developing in open areas. Below around 1100 m elevation, a rain crust can be found near the surface of the snowpack. Deeper in the snowpack, the mid-January surface hoar/facet layer is now typically down 70-100 cm. Recent observations suggest the layer has generally stabilized but isolated weaknesses may still exist, especially where buried surface hoar is still intact. Below this layer, the snowpack is generally strong and well settled. The exceptions are areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern, especially in shallow snowpack areas.