Regions
Banff Yoho Kootenay.
Steady winds have decreased the ski quality. Stick to mellow lines in thin snowpack areas to avoid triggering any basal weakness. If the sun pops out Sunday, watch for increasing hazard on solar aspects.SH
Weather Forecast
Sunday expect a weak freeze and a mix of sun and cloud and minimal new snow. Winds will be Westerly and light gusting up to 75km/h in the alpine. A forecasted waming trend Monday, Tuesday with freezing levels up to 2600m. This will be accompanied by strong W winds,10-15 cm of snow in the Louise group, and maybe even some rain W of the divide.
Snowpack Summary
New wind slabs 15-25 cm thick in the immediate lees. Western areas such as Emerald and Field have a deep and stable snowpack. Contrast this with the Lake Louise, Hwy 93 N, & Sunshine areas, where there is a weaker snowpack with sudden collapse very easy compression results on the basal depth hoar. A crust exists on all but N aspects.
Avalanche Summary
A recent sz. 2 wind slab on a N aspect was observed in Yoho from the last 24 hours out of steeper terrain. No other avalanches were reported.
Confidence
Freezing levels are uncertain on Sunday
Problems
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.
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.