Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Sunday: A band of snow arrives late in the afternoon, bringing 10-15 cm to this region. Freezing levels should stay at valley bottom and winds will be strong southerly. On Monday, unstable air will bring another 10-15 cm new snow. On Tuesday, another intense Pacific frontal system arrives, which will likely bring 20-30 cm new snow to this region, with freezing levels rising to around 1200 m. Continued strong westerly/southwesterly winds.
Avalanche Summary
An avalanche cycle up to size 2.5 was reported on Saturday. Both slab and loose snow activity was noted at all elevations.
Snowpack Summary
Dense new snow is setting up a fresh storm slab on top of the previous cold, low density snow from the last few days. An interface down 30-50 cm just above a rain crust is producing easy but resistant shears in snowpack tests. The rain crust itself lies buried around 40-60cm below the surface up to around 1900 m. The bond at this crust is reported to be quite good. On steep slopes, this interface, or the one above it, definitely has the potential to act as a good sliding surface. Weak layers lower in the snowpack have generally ceased to be of concern, except perhaps in very isolated, thin rocky areas.
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.