Riders can still trigger persistent weak layers at lower elevations. Terrain like cutblocks, steep forest openings, and gullies are suspect. Wind slabs are the primary concern at higher elevations.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
THURSDAY NIGHT: Partly cloudy, moderate west wind, alpine temperature -15 C.FRIDAY: Cloudy with light snowfall, accumulation 1 to 3 cm, moderate to strong southwest wind, alpine temperature -14 C.SATURDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, light southeast wind, alpine temperature -18 C.SUNDAY: Partly cloudy, light northeast wind, alpine temperature -21 C.
Avalanche Summary
No new avalanches were observed in the region on Wednesday.
Snowpack Summary
Wind slabs exist in open, exposed areas at higher elevations. They may be found on all aspects due to variable wind directions. In sheltered terrain, around 20 to 30 cm of recent soft snowfall may be found.The mid-January weak layer of surface hoar or faceted grains is buried around 50 to 80 cm. It is found on shaded and sheltered slopes and is most prominent between 1600 m and 1900 m but has been found up to 2200 m. It may overly a melt-freeze crust on south aspects. Snowpack test results suggest that this layer may still be triggered by humans.The middle of the snowpack is generally consolidated. The bottom half of the snowpack is unconsolidated and composed of weak and sugary faceted grains. There is potential for shallower avalanches to step down to these deeper weak layers.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.