Northwest Coastal

Snowfall and wind might ease on Friday, but this storm just doubled our snowpack depth over 3 days. Give the new snow time to settle and bond before venturing out of simple terrain. A Special Public Avalanche Warning is in effect in this region.

Moderate -

Thursday night: Mainly cloudy with light flurries beginning in the early morning. Light northwest winds shifting northeast.Friday: Cloudy with another round of flurries bringing around 10-15 cm of new snow by end of day and clearing overnight. Light northeast winds. Alpine high temperatures around -7.Saturday: Increasing cloud and flurries bringing about 5 cm of new snow by end of day and increasing overnight. Moderate to strong southeast winds increasing to extreme overnight. Alpine high temperatures around -5, increasing overnight as freezing levels rise to about 1500 metres.Sunday: Cloudy with continuing snow/rain bringing about 20 cm of new snow to upper elevations, including accumulations from overnight. Rain below about 1100-1200 metres. Winds easing from extreme to moderate southeast over the day. Alpine high temperatures around 0 to -1.

A social media report from the Shames area on Tuesday described active avalanche conditions with lots of whumpfing and numerous small (size 1) to large (size 2) natural releases observed even with poor visibility at treeline elevations. These storm slabs failed at the old snow surface, noted as a crust in this area. Although the weather has certainly been limiting observations, we can expect a continuation of this natural avalanche activity during the barrage of storms hitting the region.

Another 10-15 cm of new snow expected by the end of Friday should bring storm totals from the past few days up to about 110-140 cm, effectively doubling snowpack depths from before the storm. Strong to extreme southwest and west winds are likely forming the thickest deposits on lee slopes at high elevations. Wind effect is most pronounced near the coast.The new snow has been observed bonding poorly to the weak surface hoar and facets that formed our pre-storm snow surface. The surface hoar is likely to be especially prominent on sheltered slopes at treeline while surface faceting was likely more widespread. Deeper in the snowpack, there are reports of several crusts including an early season crust with facets near the bottom of the snowpack.Prior to the storms, there was only 70-120 cm of snow in the alpine and very little coverage below treeline, but this has seen rapid change over the week.