Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain.

Wednesday night: Cloudy with flurries bringing 10-20 cm of new snow. Strong southwest winds. 

Thursday: Cloudy with increasing snowfall bringing 20-50 cm of new snow. Strong to extreme southwest winds. Treeline high temperatures around -2 with freezing levels to 1500 metres.

Friday: Mainly cloudy, becoming clear overnight. Light southwest winds. Treeline high temperatures around -4.

Saturday: Cloudy with increasing flurries transitioning to wet flurries over the day. Possible 15-30 cm accumulation at high elevations. Treeline high temperatures around -1 with freezing levels climbing to 2900 metres by late afternoon.

Small dry loose and soft wind slab avalanches were observed during control work in the Whistler area on Tuesday. Forecast weather will step hazard up several notches as 30-70 cm of new snow blankets the region. Expect a widespread storm slab problem to form during the day, with the sensitivity and destructive potential of slabs increasing over the day. Slabs will be especially touchy in areas the new snow overlies surface hoar. This weak grain was observed on the surface in the north of the region earlier this week. 

A powerful storm pulse is expected to bring 30-70 cm of new snow to the region by end of day Thursday, with heavier accumulations favouring the south of the region. Strong to extreme winds will accompany the snowfall. 

The new snow will accumulate over mainly wind affected surfaces, however surface hoar was observed in the Whistler area earlier this week. Touchy storm slabs are very likely to form in any areas where new snow buries these weak grains. A thick crust, breakable at treeline and below, can currently be found 10-20 cm deep throughout the region. This crust is found on the surface on many windward slopes where it was exposed by recent strong winds. In the alpine, another crust exists around 100 cm down.

Average snow depths at treeline are 90-120 cm, with 200+ cm in the alpine. Snowpack depths decrease dramatically below treeline and are below threshold for avalanches in many areas. Big storms like the one we'll see Thursday are gradually changing this. Early season hazards such as rocks, stumps, and creeks are a concern at these lower elevations.

• Watch for fresh storm slabs building throughout the day.
• Storm slab size and sensitivity to triggering will likely increase through the day.
• Minimize exposure during periods of heavy loading from new snow and wind.