This forecast is based on very few field observations and a high level of uncertainty exists. A conservative approach to terrain selection is critical until more snowpack data becomes available.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Friday: 5-10cm of new snow / Moderate to strong southwest winds / Freezing level at 900mSaturday: Light flurries / Light and variable winds / Freezing level at 400mSunday: Mix of sun and cloud / Light and variable winds / Freezing level at valley bottom with alpine temperatures dropping to about -11
Avalanche Summary
No new avalanches have been reported. This may speak more to a lack of observations rather than actual conditions. A natural storm slab avalanche cycle is expected to have occurred on Thursday in response to recent wind and snowfall. The potential for human triggering of these storm slabs is expected to continue into the weekend.We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).
Snowpack Summary
Between 30 and 45cm of new snow has fallen in the past few days. I'd expect reactive storm slabs to exist in wind-exposed terrain or in places where the recent storm snow has a weak bond with a series of crusts which formed in late November which lie up to 60cm below the surface.Another feature in the snowpack is a 3-5 cm thick crust which was formed around Halloween and can be found approximately 100cm down at treeline elevations. This layer is generally stubborn to trigger; however, I'd be increasingly cautious of it in the north of the region where it may remain reactive. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 200+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own 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.