Avalanche Forecast

Moderate - Uncertainty is due to the limited number of field observations.

Wednesday night: Cloudy with isolated flurries. Light west winds.

Thursday: Mainly sunny. Light variable winds increasing in the evening and becoming strong southwest overnight. Alpine high temperatures around -8.

Friday: Cloudy with scattered flurries bringing 5-10 cm of new snow. Light to moderate southwest winds. Alpine high temperatures around -7.

Saturday: Mainly cloudy. Light south winds. Alpine high temperatures around -7.

We're still awaiting field observations from the aftermath of Tuesday's storm, however it it's safe to assume it was a very busy day for natural avalanches as up to 70 cm of new snow blanketed the region and was redistributed by strong winds. 

A few preliminary observations from the Mica dam area showed numerous natural size 1.5-2 storm slabs on northwest aspects. Only about 30 mm of rain fell in that location (likely translating to about 35 cm at higher elevations. In the Trans-Canada corridor, a size 4 (VERY LARGE) avalanche ran on Mt. Laurie. )

Looking forward, expect Thursday to be another tricky day to be in the mountains, with new and reactive wind slabs formed in wind-exposed areas and even more widespread storm slabs primed for human triggering in more sheltered areas.

An impressive 30-70 cm of new snow fell in the region during Tuesday's storm. The new snow buried wind affected surfaces at upper elevations as well as surface hoar in wind sheltered areas and a thin crust on solar aspects. 

The new snow will take time to form a bond with these previous surfaces, particularly in spots harbouring surface hoar or crust. In exposed areas, elevated winds are almost certainly redistributing new snow into reactive wind slabs and adding to cornices.

A couple of persistent weak layers exist in the upper to mid snowpack:

• The upper layer, now found an estimated 80-140 cm down, is a spotty layer of surface hoar at treeline and below. 
• The lower layer, now likely around 110-200 cm deep, is widespread and may present as decomposing surface hoar and/or a crust.

Avalanche activity on these layers has been dwindling since last week and snowpack tests results have generally indicated that they are gaining strength. Given their age (particularly the deeper layer) and the testing load brought by Tuesday's storm, the outlook is good for these layers to finally become dormant as our current surface instabilities diminish.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Avoid exposure to steep sun exposed slopes.