Winds are redistributing the recent storm snow at upper treeline and alpine elevations. Watch for areas of wind-affected "chalky" or "pillowy" snow.
Confidence
High - The weather pattern is stable
Weather Forecast
FRIDAY: Mix of sun and cloudy, light flurries. Accumulation trace. Ridge wind light from the northwest becoming southwest. Temperature -3. Freezing level 400 m.SATURDAY: Mostly sunny. Ridge wind light from the east. Temperature -4. Freezing level 400 m.SUNDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind light from the southeast becoming south. Temperature -5. Freezing level surface.
Avalanche Summary
On Wednesday a natural Size 2 slab avalanche was reported on a southeast aspect at 1400 m on the North Shore mountains, as well as a Size 1 on a west aspect at 1200 m. Ski cutting however produced no results.On Tuesday a few natural, loose dry avalanches were observed in the recent storm snow. Ski cutting also produced storm slab and loose dry avalanches to Size 1 running far on the December 18th crust. And explosive control work produced storm slab avalanches up to Size 1.5, propagating about 40 m wide with crowns 20-25 cm deep, failing on the December 18th crust.
Snowpack Summary
Northerly winds have redistributed the recent storm snow scouring windward, northwesterly slopes and loading leeward southerly slopes in the alpine and exposed treeline areas. Approximately 20-30 cm of storm snow sits on top of the most recent December 18th melt-freeze crust which formed following Sunday's rain event to upper treeline elevations. Below this crusts lies 20 cm of wet snow which appears to be well bonded to the lower December 16th crust. Below this second crust the snowpack is well settled to ground. Snowpack depths are about 125 cm at 1100 m elevation, with many early season hazards present at lower elevations.
Problems
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.