Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Banff Yoho Kootenay.
The avalanche cycle continues with many natural, human and explosive triggered avalanches occurring everywhere. Avoid avalanche terrain; this situation is very touchy and several close calls were had today. More snow and wind expected for Monday.
Weather Forecast
Another 10-15cm is forecast on Sunday night, tapering my mid-day Monday. Extreme wind warnings are in effect, with gusts up to 110 km/hr expected. Temperatures will remain between -5 and -10. The longer range forecast shows this storm system to dissipate by Tuesday, leading to a drier week ahead.
Snowpack Summary
45cm of storm snow has fallen over the last few days, combined with very strong winds. Deep storm slabs have formed from new snow and wind loading; in excess of 100 cm in leeward areas. These slab are overloading a weak, facetted snowpack. WIth another 15 cm expected by mid-day Monday, this critical situation will persist for a few more days.
Avalanche Summary
Large natural and explosive controlled avalanches continue to occur in many areas, including slopes adjacent to the ski area boundaries. Numerous human triggered avalanches adjacent to the ski areas, including Maintenance Cliffs near Lake Louise and a very close call on Wawa Ridge. Avoid all avalanche starting zones on Monday.
Confidence
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.