http://www.pc.gc.ca/apps/links/goto_e.asp?destination=http://www.facebook.com/ParksMountainSafetyNice weather weather is on the way but the instabilities we have within our snowpack are not likely to heal anytime soon. Cautious backcountry travel and wise decision making will be needed.
Weather Forecast
A high pressure ridge is slowly building over the Interior with a more northerly flow. Forecast is for overall clearing with a weak disturbance passing over the Province tonight into tomorrow morning. Light snow, ~5mm and light to moderate westerly winds tonight. Clearing by Sunday, cold temperatures and dry conditions will prevail for the week.
Snowpack Summary
Up to 15cm overnight on top of the 50-70cm deep storm slab sits on a well preserved and widespread Dec 17th surface hoar layer (10-20mm). The surface hoar sits on top of a rain crust up to 2100m, and on well settled snow above 2100m. The Dec 9th surface hoar layer is down 80cm in the area. The Nov 9th crust is 30cm up from the ground.
Avalanche Summary
Yesterday1 natural avalanche size 2.5 east of the Rogers Pass summit north aspect from one of the gullies off of Mt Macdonald. Artillery control from two days ago produced numerous avalanches up to size 3.5 showing wide propagation within the highway corridor. Some stepping down to deeper layers.
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.