Fresh wind slabs may be touchy to rider triggers.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A series of Pacific frontal systems will hit the Interior region starting tonight and continue through next week. Each system will be a bit stronger bringing moderate to heavy snow amounts and strong winds. Sunday: Cloudy, alpine temperatures -14 with West winds 30-50 km/h. New snow 5-10 cm.Monday: Snow 15-25 cm with alpine temperatures near -12 and ridgetop winds southwest 30-70 km/h.Tuesday: Snow 5-10 cm with alpine temperatures -10 and ridgetop winds light from the southwest.
Avalanche Summary
No new avalanche reports for Friday. Recent reports from Thursday indicated natural cornice and ice falls from 2300 m and above on NW and SW aspects, triggering either a small wind slab or entraining surface snow on the slopes below. Loose dry sluffing from steeper terrain may push you off your line, so watch and avoid terrain traps below. With forecast strong winds fresh wind slabs may build and be triggered by light loads (skiers/ sledders).
Snowpack Summary
Recent wind has formed wind slabs on a variety of aspects in the alpine and at treeline. The persistent cold temperatures have developed facets near the surface and new surface hoar growth in sheltered locations. There may be a layer of surface hoar buried 20-40 cm deep in sheltered areas, especially in the Dogtooth Range. This layer may me reactive with additional load in certain areas. Alpine snow depths are around 120-170 cm, and the widespread mid-November crust is buried down around 70-90 cm. In shallower snowpack areas reports indicate that the bond to the crust is weakening. If you dig down to the crust, watch for facets (sugary crystals) developing above and below. This may provide a hard surface with a weak sliding layer in the future.
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.