Purcells

The main storm pulse isn't expected in the Purcells until Saturday evening. Watch for thin new wind slabs building in advance of the storm, as well as widely varying snowfall amounts that favour the interior and west of the region.

Moderate - Forecast snowfall amounts are uncertain

Friday night: Cloudy with flurries bringing 2-6 cm of new snow. Moderate southwest winds, increasing overnight.Saturday: Cloudy with continuing flurries bringing 5-15 cm of new snow by end of day, peaking in the evening, with possibly greater accumulations in the centre of the region. Moderate to strong southwest winds. Alpine high temperatures around -4 as freezing levels rise to 1500 metres.Sunday: A mix of sun and cloud with isolated flurries and a trace of new snow. Moderate northwest winds decreasing over the day. Alpine high temperatures around -10.Monday: A mix of sun and cloud. Light variable winds. Alpine high temperatures around -12.

Avalanche control work on Wednesday and Thursday produced both large and small persistent slab avalanches (size 1 to 2.5) on north facing terrain between 1900 and 2400 m. On Monday and Tuesday control work produced avalanches to size 3 on steep north, northwest and northeast facing features between 1900 and 2700 m. One of the more interesting results was a size 1.5 wind slab that was remote triggered from 200 m away on a north facing slope around 2100 m. On Sunday, a large (size 2.5) persistent slab avalanche was triggered by a snowmobiler in Silent Pass. The avalanche occurred on a wind loaded northwest-facing slope in the alpine. See details in the MIN report. Last weekend explosive control work produced numerous large persistent slab avalanches (size 2-4) in alpine terrain. The avalanches occurred on all aspects and failed on several different weak layers including the early December weak layer and weak facets at the bottom of the snowpack. Over the past two weeks, several large persistent slab avalanches were remotely triggered from skiers on adjacent slopes, particularly in the Golden area. There's a great summary of recent avalanche activity from SkiingGolden here.

Light snowfall has begun to bury 5 to 15 cm of older low density snow on the surface. This older snow sits on wind-affected surfaces in the alpine, and in some isolated areas above small surface hoar (feathery crystals).A weak layer that formed during the dry spell in early December is now 80 to 110 cm deep. The layer is composed of facets (sugary snow), surface hoar (feathery crystals), and a sun crust (on south aspects). Another similar weak layer is buried 90 to 150 cm. Finally, the base of the snowpack has weak faceted layers at alpine and treeline elevations. All of these weak layers have been producing large avalanches as recently as December 25th. Human triggering any of these layers is most likely on slopes that didn't previously avalanche and on slopes that have variable snowpack depth (such as rocky alpine features).