Regions
Banff Yoho Kootenay.
We continue to expect human triggering to be likely in many areas, so watch for slopes that have not yet avalanched yet this winter as they may be primed to go and just waiting for a trigger.
Weather Forecast
A SW flow over the area will keep temperatures relatively warm over the next 24 hours. Expect up to 5 cm in flurries tonight and Thursday, along with temperatures from 0 to -9 and light winds from the south. Not bluebird, but a nice few days with a few cms of snow every day through the week.
Snowpack Summary
Fresh windslabs and cornice growth in the alpine with 15 to 30 cm of recent snow and west winds. A 50-100 cm slab overlies the January 6th weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. The lower snowpack is facetted and quite weak in thinner areas (<1.5m) and settled in thicker areas.
Avalanche Summary
Avalanche activity has slowed down slightly, but we are just coming out of a natural cycle and have had many close calls in the last week indicating that human triggering remains likely in many areas. Today we observed a fresh size 2 avalanche on the slopes of Mt Jimmy Junior (Bow Summit area), SE aspect at 2300m.
Problems
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.
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.