Wind slabs may remain reactive to human triggering. As you enter wind-affected terrain, watch for wind slabs on all aspects.
Wind slab will exist on various aspects in exposed terrain and around ridgelines. Last weekend's storm initially came in with southwest winds, but with the intrusion of arctic air, winds switched to the northeast, building slabs in less common locations.
These slabs have formed on top of a widespread crust and may bond poorly to this hard surface.
The ridge Increasing cloud cover on Thursday, with a shift in the weather pattern bringing snowfall for the weekend.
Wednesday Overnight: Snowfall easing. Alpine temperatures around -15 C. Light to moderate northwesterly winds.
Thursday: Partially cloudy. Alpine temperatures around -15 C. Light to moderate northwesterly winds.
Friday: Partially cloudy. Freezing level rising to 1000 m. Alpine temperatures around -8 C. Light to moderate westerly winds.
Saturday: Cloudy with light snowfall. Freezing level rising to 1000 m. Strong to extreme southwesterly winds.
Arctic air invaded the province on Monday and Tuesday, the resulting strong northerly winds redistributed the storm snow into wind slabs on southerly aspects. Several natural avalanches occurred on southerly aspects as a result of this wind-loading. Check out our field team's MIN report from Pine Pass during this period.
Throughout the storm last weekend, limited observations were been made with poor visibility, but we expect a natural avalanche cycle occurred on Saturday. During the peak of the storm on Saturday, several large natural storm slab avalanches were reported from treeline elevations in the Kakwa.
Last weekend's storm brought 20-100 cm of new snow. Recent northeasterly winds have been redistributing this new snow into wind slabs in lee areas and creating a heavily wind-affected surface in the alpine and exposed treeline. This new snow overlies a widespread crust created from a rain event in early February. This 1-20 cm thick crust exists on all aspects and elevations.
Below the crust, 10-40cm of more settled snow exists above the late January weak layer. This layer consists of weak faceted snow, a melt-freeze crust, and surface hoar crystals in isolated sheltered areas at treeline and below. In most areas, this layer is bridged by the thick crust above it. It is currently considered dormant but could become active later this season.
The lower snowpack is generally strong and well-bonded. The base of the snowpack is expected to be weak and faceted in shallow, rocky slopes east of the divide.
