http://www.pc.gc.ca/apps/links/goto_e.asp?destination=http://www.facebook.com/ParksMountainSafetyReactive avalanche conditions have been observed for the past week. This is one of those problems that takes a while to disappear. Be diligently conservative in your terrain selection.
Weather Forecast
A weak system will be crossing the Interior today giving us light snow ending this evening. Tomorrow will be partly cloudy with lingering flurries. A high pressure ridge is in the works and its effects will be seen starting Monday with colder temperatures and clear skies.
Snowpack Summary
9cm overnight. The widespread Dec 17 surface hoar layer is down ~50-80cm which sits on top of a thick rain crust up to 2100m. A 2cm facet layer between the rain crust has been reactive in snowpack tests with easy results. The Dec 9 surface hoar is down ~ 70-90cm but is more spotty in distribution. The Nov 9 crust is 30cm up from the ground.
Avalanche Summary
Backcountry report from top of Grizzly Shoulder to Puff Daddy, NE facing bowl feature, remotely triggered size 2.0 avalanche, ~2000m, down 50cm, 40-50m wide, 100m long. A second report of a rider triggered avalanche size 1.5 down 55cm and 10-20m wide from another feature in the same area.
Confidence
Due to the number of field observations
Problems
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.
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.