The incoming snow is burying a new weak layer. On Friday, deeper wind loaded slopes may have enough new snow for avalanches on this layer.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
THURSDAY NIGHT: Light flurries with localized accumulations of 5 cm, light southwest wind, alpine temperatures drop to -8 C.FRIDAY: Light flurries with another 5 cm of snow, light to moderate southwest wind, alpine high temperatures around -4 C. SATURDAY: 5-15 cm of snow, strong southwest wind, freezing level climbing to 1300 m, alpine high temperatures around -2 C.SUNDAY: Light flurries in the morning then clearing in the afternoon, moderate west wind, alpine high temperatures around -4 C.
Avalanche Summary
No notable avalanche activity has been observed in the past few days.Earlier in the week there were small loose snow avalanches (mostly on sunny slopes) and isolated cornice falls and wind slabs (mostly on north and east facing slopes). On Tuesday, a small cornice fall triggered a size 2 persistent slab avalanche. The avalanche occurred in north-facing glaciated terrain in the Selkirks and appeared to have stepped down to glacier ice (100-200 cm deep).
Snowpack Summary
Although incoming snowfall amounts are on the lighter side, the snow is burying large surface hoar crystals and sun crusts. This will create the potential for fast moving sluffs and thin slab avalanches with wide propagations. The most suspect terrain features are steep slopes and rolls below 2000 m (where the largest surface hoar exists) and steep south-facing slopes in the alpine (where sun crusts exist).The middle and lower portions of the snowpack are generally well-settled and strong. Professionals are tracking a layer around 130 to 180 cm deep, composed of weak faceted grains, surface hoar, and a sun crust. The chance of triggering this layer is low. In shallow snowpack areas, the base of the snowpack may also still be composed of weak faceted grains.
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.