It is still possible to trigger large avalanches. Hazard will fall as the temperature drops, but forecasting when and how this will happen is challenging. It would be prudent to keep things conservative until the snowpack cools off and settles.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Sunday
Weather Forecast
FRIDAY: snow starting in the morning with accumulations of up to 5cm through the day. SATURDAY: 5-8cm snow overnight, flurries through the day. SUNDAY: Up to 10cm of snow. Winds will be light from the west through the forecast period. Freezing levels will hover at 1500m.
Avalanche Summary
A continued cycle of natural loose wet sluffs reaching Size 2 has been associated with daytime warming over the last couple of days. A natural Size 1.5 avalanche was observed in the Kicking Horse slackcountry on Thursday that apparently ran on a reloaded bed surface in a wind loaded feature. The interface is suspected to be the early January weak layer. Natural persistent slab avalanche activity was also observed earlier in the week, with a report of two Size 2.5s also in the Kicking Horse backcountry, that also released on the surface hoar, facet and crust weakness as deep as a meter down.
Snowpack Summary
Wet surface snow capped by a supportive melt freeze crust can be found on solar aspects and at lower elevations, Dry snow can still be found on high north facing terrain. New surface hoar growth may be found at and below treeline on shaded aspects. Sustained winds have scoured north and west-facing alpine slopes and formed fresh wind slabs and cornices. The early January surface hoar/ facet layer is typically down 70-90 cm. Recent very large avalanches have been failing on this interface in the north of the region (see avalanche discussion) and it continues to produce sudden planar results in snow pit tests. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.
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.