Adopt a conservative mindset. Watch for signs of reactive windslab, and avoid thin, rocky start zones. Large wind slabs continue to be triggered by riders, and the early December crust/facet layer is still haunting us.
Up to 10 cm of recent snow and coninued strong wind has formed wind slabs that remain reactive to rider traffic.
Slabs may be more reactive where they sit on surface hoar or crusts.
Be extra cautious at ridge crests and on convex rolls.
Natural cornice fall is possible with solar radiation. As natural avalanches taper off, cornices could still be sensitive to a human trigger.
Cornice fall could be a hazard on its own and it could trigger a deeper slab avalanche from the slope below.
The early December crust can be found 90-160 cm deep.
This deep persistent slab problem has been less active over the weekend, but we have been reminded multiple times in the last month that this layer could remain a concern all winter.
Thin rocky start zones are the most likely place to trigger this layer. Also, daytime warming, solar radiation, cornice fall, and step-downs from smaller avalanches could increase the chance of an avalanche on this layer.
Sunday Night: Mostly clear. No new snow expected. Freezing levels fall to valley bottom, alpine low around -5 C. Light northwest wind trending to strong at higher elevations.
Monday: Mostly cloudy. 0-2 cm of snow expected. Light north wind trending to moderate northwest at higher elevations. Freezing level at valley bottom in the morning, rising to 1000 m by the afternoon. alpine low around -7 C.
Tuesday: Partly cloudy. No new snow expected. Light southwest wind, trending to strong northwest at higher elevations. Freezing level at valley bottom overnight, rising to 800 m by the afternoon.
Wednesday: Partly cloudy. No new snow expected. Light west wind, trending to extreme northwest at higher elevations. Freezing level at valley bottom overnight, rising to 600 m by the afternoon.
On Sunday, a professional operation west of Panorama reported a size 2.5 natural windslab avalanche that appeared to have been triggered by a falling cornice. It was on a south aspect in the alpine.
On Saturday, a several rider triggered wind slab avalanches up to size 2 were reported near Golden. They were on north through southeast aspects at treeline and above. See this Mountain Information Network post for pictures and more information about one of them.
Additionally, a natural cornice fall from a south aspect in the alpine triggered a size 2.5 avalanche in extreme terrain that ran into rideable terrain below, and several loose, solar triggered avalanches were reported.
Also, west of Invermere, a small, rider triggered avalanche was reported to have failed on the early December persistent weak layer. The snowpack may be shallower in this location, making this layer easier to trigger, but it's a good reminder that this crust/facet combo is still active.
Over the last week, the early December persistent weak layer has produced a few large natural avalanches (2-3) in the center of the region. Explosive controls have also produced a few size 2 avalanches that failed on the same persistent weak layer, one being remotely triggered. These occurred on thin to thick features on northeast-facing slopes from between 1600 m and 2000 m, where the layer was buried 100 cm + deep.
Professional operations across the region are reporting surface hoar growth from 2 mm all the way up to 12 mm, and a thin crust on steep solar aspects in areas that saw the sun on Friday or Saturday. On the far northern end of the region, the surface seems to be mostly wind effected.
Up to 10 cm of recent snow and strong winds have formed pockets of reactive wind slab, especially where it sits above surface hoar and crusts.
Around 1900 m and below, a crust is now capping the dense 10-30 cm of snow which has settled significantly with the past mild temperatures. The crust varies from thin to thick, according to the aspect and elevation. Below this, a layer of surface hoar and melt-freeze crusts are found, which seems to be still reactive in isolated areas.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 90-160 cm. This layer was reactive early last week producing large size 3 avalanches.
Activity has tapered, however, daytime warming, sun, cornice fall, and human triggers from steep, rocky slopes, with a shallow or thin-to-thick snowpack may still be able to trigger this weak layer.
