Regions
Northwest Inland.
Weak sugary snow in the bottom third of the snowpack continues to be a concern, as there is potential for large human triggered avalanches failing at this interface.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Wednesday
Weather Forecast
Dribs and drabs of snow are expected for the first half of the week before the potential for a more significant system comes into play on Thursday.MONDAY: Scattered cloud cover, freezing level at valley bottom, light to moderate north/northwest wind, no significant precipitation. TUESDAY: Broken cloud cover, freezing level at valley bottom, moderate southwest wind, scattered snow showers. WEDNESDAY: Broken cloud cover, freezing level at valley bottom, moderate to strong southwest wind, 1 to 5 cm of snow. Visit avalanche.ca/weather for a more detailed mountain weather forecast.
Avalanche Summary
On Saturday wind slabs to size 1.5 were triggered by skiers on E aspects between 1600 and 1850 m. Previously, there was a report of a size 2.5 natural avalanche in the northern part of the region. This may have happened in the last 4 days and possibly failed on a persistent weak layer buried early february on a NW aspect in the alpine.
Snowpack Summary
10 to 20 cm of storm snow accumulating in the last week has been transported by the wind, and now sits on a variety of old surface conditions including isolated wind slabs, pockets of soft snow (5 to 10 cm deep), sun crusts, and surface hoar. A supportive rain crust exists below 1000 m. A layer of surface hoar that was buried on February 10th may exist 30 to 60 cm below the surface, but there's a fair bit of uncertainty regarding the reactivity and distribution of this layer. A stiff mid pack sits above weak sugary snow near the ground. Although possibly dormant, this basal weakness has the potential to produce very large destructive avalanches.
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.