Regions
Banff Yoho Kootenay.
A short intense storm is currently forecast for Friday. Expect increasing danger throughout the day, peaking Friday night. Stick to very conservative terrain and avoid overhead exposure until after the storm has abated. SH
Weather Forecast
A 24 hour long system will roll into the region Friday AM with 3000m winds up to 100kmh, 2000m winds around 40kmh and 20-30cm of snow. Temperatures will be around -10C in the alpine and -3 to -5C at 2000m. Winds will die down and temperatures will cool off Saturday and Sunday.
Snowpack Summary
There is variable amount of wind slab development at tree line and above. Below 1850m a thin rain-crust sits below 10-15cm of recent snow. Common throughout the region are the weak facets and depth hoar in the lower half of the snowpack, overlain by a 40-60 cm slab of well settled snow.
Avalanche Summary
No new avalanche activity was observed or reported on Wednesday.
Confidence
Forecast snowfall amounts are uncertain on Friday
Problems
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.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.