Regions
Northwest Inland.
Changing wind directions may develop new wind slabs on Thursday.
Weather Forecast
Tonight: Mostly clear with moderate northerly winds and alpine temperatures around -15. Thursday: Mix of sun and cloud with strong northerly outflow winds and alpine temperatures around -17. Friday: Clear with strong northeast outflow winds and alpine temperatures around -15. Saturday: Overcast with flurries or light snow and moderate to strong northwest winds.
Avalanche Summary
Report on Tuesday of a size 2.0 avalanche on the "5000" run off Hudson Bay Mountain in Smithers. This was a visual report from town, the sliding surface is unknown but suspected to be the recent storm snow.
Snowpack Summary
10-15 cm of recent storm snow has been transported by the wind, and now sits on a variety of old surface conditions including isolated wind slabs, pockets of soft snow (5-10 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 30-60 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.