Regions
Banff Yoho Kootenay.
Be aware that a strong alpine temperature inversion has created warm conditions in alpine start zones. With uncertainty over the October 31 layer lingering: Ice climbers and skiers alike should carefully consider their exposure to overhead terrain.
Weather Forecast
A ridge of high pressure will continue to dominate the weather through Saturday with clear skies, light winds (although higher in east - west valleys), and a strong alpine temperature inversion. As the inversion established itself Thursday afternoon , temperatures reached 3C at 3000m while 2000m temps only reached -7C.
Snowpack Summary
Suncrusts are developing on steep south slopes with a temperature inversion. Surface hoar up to size 10 has formed. Below 2500m, 30 -50 cm of snow lies over the Nov 27th and Nov 23rd crusts. Both of these now overly the Halloween crust/ facet layer that sits 30-50cm above the ground. This lower layer is a facet layer above 2500m and a crust below.
Avalanche Summary
No avalanches were observed or reported at the time of writing although temperatures have spiked to over 3 degrees C at 3000m due to a strong temperature inversion.
Confidence
Freezing levels are uncertain
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.