Regions
Banff Yoho Kootenay.
http://www.pc.gc.ca/apps/scond/Cond_E.asp?oID=15678&oPark=100092Natural activity has tapered off, but forecasters have low confidence in the snowpack due to the basal weaknesses. Now is not the time to venture into big terrain. SH
Weather Forecast
Freezing levels will stay near bottom, and alpine temperatures will stay well below freezing on Sunday. Expect light winds, a mix of sun and cloud, and no snow for the next few days.
Snowpack Summary
Windward features are mainly scoured to rock from last weeks storm. Widespread windslabs in lee and cross loaded features at treeline and above. Easy, sudden collapse compression results were found at treeline on Hwy 93 N today (E side of the highway), collapsing in the basal depth hoar. Some moist snow below treeline on solar aspects in the PM.
Avalanche Summary
One notable size 3 occurred in the last 24 hours on a solar alpine feature near Mt. Hector, stepping to ground. Most natural activity has ceased. Evidence of the widespread cycle from the last week is sobering, with many features having gone wall to wall on the basal layers.
Confidence
Due to the number of field observations on Saturday
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.