The region has just received well over a metre of snow, and destructive avalanches are still a real possibility. Give the snowpack time to gain strength before pushing into steep terrain.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Sunday: 5-15cm of new snow / Moderate to strong southwest ridgetop winds / Freezing level at 900m. Monday and Tuesday: Mix of sun and cloud / Light and variable winds / Freezing level at about 900m
Avalanche Summary
In recent days, widespread storm slab avalanche activity was triggered naturally or with explosives. Most of the avalanches observed were in the size 2 range; however, a few size 3 and 3.5 avalanches were observed running in large, lee alpine features. With ongoing snow and wind on Saturday and Sunday afternoon, I'd be on the look-out for continued destructive storm slab activity, especially in higher elevation lee terrain.
Snowpack Summary
With ongoing stormy weather, snow depths have increased rapidly over the past week bringing treeline snow depths to 180-220 cm. Much of the snow from Wednesday and Thursday has settled and gained significant strength. That said, more recent systems have created large and reactive storm slabs which appear to be especially touchy in higher, wind-exposed terrain. Over a metre below the surface you'll find the thick mid-November crust. The reports we've received suggest a reasonable bond at this interface. Below this, the snowpack is reported to be strong and well-consolidated. A significant change from even a week ago is that we are now above threshold for avalanches below treeline (think cutblocks and open areas in the forest), so heads up as you work your way towards treeline. Nice to see mid-week posts to the Mountain Information Network... all observations are useful so please keep 'em coming!
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.