The primary concern is persistent weak layers lurking in the snowpack. These types of problems take time to heal, and are best managed with patience and conservative terrain choices.
Confidence
Moderate - The weather pattern is stable
Weather Forecast
SATURDAY NIGHT: Isolated flurries with trace amounts in northern and eastern parts of the region and up to 6 cm in southwestern parts of the region, moderate wind from the southwest, alpine temperatures drop to -12 C.SUNDAY: Isolated flurries with localized accumulations of 2-4 cm, light wind with moderate gusts from the southwest, alpine high temperatures around -8 C.MONDAY: Mix of sun and cloud, light wind from the west, alpine high temperatures around -8 C.TUESDAY: Mix of sun and cloud, light wind from the west, alpine high temperatures around -10 C.
Avalanche Summary
Large persistent slab avalanches continue to be reported on a regular basis. Natural activity quieted down on Saturday, but large persistent slabs were still reactive to explosive triggering.A widespread natural cycle occurred on Thursday and Friday with large (size 2-3) persistent slab and storm slab avalanches on all aspects. Some of these avalanches involved the full depth of the snowpack with up to 200 cm thick crowns.Over the past week there have been several notable large persistent slab avalanche that have been remotely triggered from skiers on adjacent slopes, particularly in the Golden area. Given this weak snowpack structure, human triggering will likely continue to be a concern on slopes with thin or variable snow depth and on slopes that did not previously avalanche.
Snowpack Summary
Strong wind from the southwest and northwest has formed wind slabs in the alpine and around treeline. Approximately 50-100 cm of recent snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals), and a sun crust (on south facing slopes) that formed during the dry spell in early December. Another similar weak layer is buried 80-150 cm. Finally, the base of the snowpack has weak facets layers at alpine and treeline elevations. All of these weak layers have been producing large avalanches over the past week. Human triggering any of these layer is most likely on slopes that didn't previously avalanche and on slopes that have variable snowpack depth (such as rocky alpine features).
Problems
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.
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.