Regions
Banff Yoho Kootenay.
Storms are on the horizon! Heads up for changing conditions and adapt your mindset to reflect the elevated danger ratings!
Weather Forecast
A couple of systems are on track to bring some precipitation in the next few days. It has already started snowing as of this afternoon and we can expect 5-10 cm overnight on Tuesday with moderate to strong SW winds. A short break on Wednesday PM and then another 5 - 15 cm overnight Wednesday and into Thursday. 1500 to 1700 m freezing levels.
Snowpack Summary
20-50 cm of new snow overlies the January 6th surface hoar/ facet layer. This layer is most prominent and reactive in the Kootenay region. In the alpine, this snow has been blown into fresh windslabs by moderate SW winds. The middle of the snowpack is facetted which has allowed recent avalanches to gain mass. A rain crust exists below 1500 m.
Avalanche Summary
Monday's avalanche control work in Kootenay resulted in widespread avalanches between size 2 and 3 with fracture lines ranging from 25-50 cm deep failing on the Jan 6th layer of surface hoar and facets. On Tuesday, local ski hills reported several size 1.5 -2 windslabs triggered with explosives in steep alpine terrain.
Confidence
Timing, track, or intensity of incoming weather system is uncertain
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.