Avalanche Forecast

Moderate - Due to the number of field observations

MONDAY: Cloudy with up to 5cm new snow from scattered flurries. Temperatures near -5 C at treeline elevations with freezing level near 1300m. Wind SW light to moderate.TUESDAY: Cloudy with sunny periods and no new precipitation. Temperatures as warm as a couple of degrees below freezing with freezing level near 1500m. Wind light from the east.WEDNESDAY: Cloudy with flurries bringing up to 10 cm new snow. Temperatures between -5 C and -2 C near treeline elevations with freezing level near 1400m. East wind with light to moderate strength.

On Saturday there was an accidentally triggered size 1.5 wind slab reported in the Whistler backcountry. I think this kind of shallow wind slab in alpine terrain is representative of the ongoing wind slab concern: localized pockets, lee and cross-loaded features, around 20 to 40 cm thick. Saturday's fatal avalanche accident on Mt. Harvey, although not in the Sea To Sky region, does highlight several of the risks posed by cornices: multi-ton snow boulders serve as large triggers potentially releasing large avalanches on the slopes below, they can break well back making for tricky travel along ridge crests. It's all the more tricky when visibility is obscured in fog or heavy snow, if the easiest pathway (flat, hard snow, open straight line) is within the danger zone, or when they're so big that you need to be 10 or 15 or more metres back from the edge to remain safe.

Recent snow in the last few days built wind slabs, primarily on northerly aspects at alpine and treeline elevations. They should stabilize quickly with warm temperatures but isolated wind slabs behind ridges and similar terrain may linger. Expect multiple crusts in the upper snowpack, especially on southerly facing (sunny) slopes. Thin crusts with facets above are possible; southerly aspects are complex and hard to forecast. Personally, I'd try to avoid them until corn season. Finally cornices are large and remain a concern: yesterday's fatal accident near Lions Bay illustrates the danger of them breaking off, and the large avalanches they can trigger.