Regions
Banff Yoho Kootenay.
While the danger rating is moderate by definition, forecasters still have low confidence in certain areas of the forecast region (Lake Louise). Exercise restraint and make conservative terrain choices for a few days yet.
Weather Forecast
Finally, some respite from the cold temps with increases warming to the -10 range through Thursday. Increased cloud cover and small amounts of precip up to 5mm. Wind will shift from North to West and decrease in velocity late on Thursday.
Snowpack Summary
20-30 cm of last weeks storm snow sits over top of the Dec 19 layer facet layer which in turn sits on the Nov 12 crust. Winds over the past week have created wind slabs in exposed areas. In many places these wind slabs sit on a weak snowpack comprised of facets and depth hoar.
Avalanche Summary
No natural activity was reported or observed today. However, Lake Louise and Sunshine Village patrollers/forecasters were able to trigger a few wind slabs with explosives up to size 2.
Confidence
Wind effect is extremely variable
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.