It's dumping and blowing and overloading a weak surface hoar layer. Avalanches are expected today and will likely run full path. Avoid exposure to avalanche terrain, including crossing paths that are still filled with alder in the valley bottom!
Weather Forecast
The storm parked over us will bring up to another 20cm today, with strong SW ridge-top winds. Fortunately freezing levels should stay below 1600m. The next pulse is expected to arrive later on Saturday bringing up to another 50cm, with strong alpine winds and freezing levels around 1600m. Wet, windy and warm; perfect for a natural avalanche cycle!
Snowpack Summary
~50 of storm snow now sits on the widespread Remembrance Day surface hoar layer. With continued loading it is forming a slab. Test results indicate the surface hoar is easily triggerable, and as the slab develops it is capable of producing large avalanches. SW winds are adding to the slab properties in lee features at alpine and tree-line.
Avalanche Summary
By yesterday afternoon the snow over the Nov 11 surface hoar layer was forming a soft slab. Skiers reported cracking and small skier triggered slabs. Recent natural avalanches have been occurring from steep, alpine terrain but running into the alder in the avalanche run-outs. The size 3.5 avalanche off of Bruins Ridge on Sunday opened many eyes.
Confidence
Timing, track, or intensity of incoming weather system is uncertain
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.