Purcells

Warming this weekend will elevate the avalanche danger. Pay particular attention to steep lines off ridges and sun affected slopes.

Moderate - Freezing levels are uncertain

THURSDAY NIGHT: Dry, cooling overnight.FRIDAY: Dry with a mix of sun and cloud. Freezing levels rising to around 1400 m. Alpine temperatures around -2C. Light southerly winds.SATURDAY: Dry and sunny. Inverted conditions with an above freezing layer between 1800m and 2500m. Light southerly winds.SUNDAY: Dry and sunny. Inverted conditions with an above freezing layer between 1800m and 2500m. Light southwesterly winds.

On Tuesday, a cornice fall triggered a persistent deep slab avalanche in the north of the region. The avalanche was very large (size 3.5) and released to ground, on a northerly aspect in alpine terrain. A close call (here) also occurred south of the Bugaboos when a group remote-triggered a size 2.5 avalanche from a ridge top. Additionally there were several other reports further south in the region of natural and explosives triggered persistent slab avalanches to size 3.5 on northwest aspects in the alpine.On Monday, a large (size 3) avalanche was triggered by a skier in the north of the region. It is likely that it released on weak faceted grains near the base of the snowpack, as described in the snowpack summary.On Sunday, a small (size 1.5) skier-triggered avalanche was noted in the north of the region. It occurred in steep terrain above a cliff and the avalanche released to the ground, likely within the weak snow described in the snowpack summary.These reports indicate that basal instabilities are still possible to trigger by humans, particularly in the north of the region.

Wind slabs are reported as being widespread in lee and cross-loaded terrain features at treeline and alpine elevations. Wind slabs may be found on all aspects due to variable wind directions.Of concern are the are deeper weaknesses in the snowpack. There is a weak layer around 80 to 120 cm deep, composed of sugary faceted grains, feathery surface hoar, and a sun crust. The base of the snowpack may also still be composed of weak faceted grains. A few large avalanches have recently run on one or other of these layers (see Avalanche Activity Discussion). The possibility of triggering these layers will likely increase with anticipated warm weather. Triggering is also more likely on south-facing slopes and in areas where the snowpack is shallow.