Avalanche Forecast

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

Wednesday night: Diminishing flurries bringing 5-10 cm of new snow. Strong southwest winds easing to light by morning.

Thursday: Mainly sunny. Light southwest winds. Treeline high temperatures around -7 with freezing levels back to 1000 metres.

Friday: Initially clear but clouding over by afternoon. Light east winds. Treeline high temperatures around -7.

Saturday: Cloudy with scattered flurries bringing 5-10 cm of new snow. Moderate southwest winds. Treeline high temperatures around -6.

Although details are still limited, a natural storm slab avalanche cycle occurred over Tuesday night. It's safe to assume numerous large or even very large avalanches occurred during this period. Some avalanches likely involved persistent layers discussed in our snowpack summary, which were active during the previous atmospheric river event. 

A report from explosives control in the Duffey Lake area Wednesday showed debris from releases up to size 2 (large) reaching quite low in tracks and runouts, aided by old debris from the last storm's avalanche cycle.

Looking forward, alpine areas where dry snow accumulated during the storm will remain a real concern for Thursday. Cooling temperatures should aid in stabilizing the snowpack but the alpine may need more time to adjust to the significant load of new snow.

The warm, wet storm from early in the week brought 20-30 mm of precipitation to the region. Above an estimated 2100 metres, this fell as snow under the influence of strong southwest winds. This added to the load over a layer of surface hoar now down an estimated 90-120 cm as well as a a deeper crust/facet combo layer that produced large avalanches during the region's last storm (Saturday).

Rain-wetted surfaces below about 2100 m will see a refreeze over Wednesday night that should effectively lock the snowpack in place at lower elevations.

Average snowpack depths in the alpine are now likely closer to 150-200 cm. Below treeline, depths of 30-50 cm have been reported around 500 m, decreasing dramatically with elevation, and still below threshold for avalanches in many areas. Early season hazards such as rocks, stumps, and creeks are still a concern below the alpine.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Watch for areas of hard wind slab on alpine features.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.