There have been a few recent close calls in the north of the region near Golden where very large human-triggered avalanches have been reported in the last week. Conservative terrain selection remains critical.
Weather Forecast
FRIDAY: 5cm new snow through the day, moderate to strong southerly winds, freezing level rising to 1300m. SATURDAY: up to 10cm overnight with lingering flurries through the day, moderate westerly winds, freezing level of around 1000m. SUNDAY: flurries, light westerly winds, freezing level returning to valley floor overnight before rising to 1300m through the day.
Avalanche Summary
On Tuesday a skier triggered a size 2 wind slab near Panorama but was able to escape without being buried. On Monday, a size 2 wind slab was accidentally triggered by a skier in the backcountry around Golden. On Saturday a size 3 sledder-triggered avalanche occurred in the Gorman Creek riding area near Golden. The early January interface is the suspected weak layer. Around the same time, a size 3.5 skier-triggered persistent slab avalanche occurred a few drainages to the south of Gorman Creek on a north-facing alpine slope. Destructive persistent slabs are expected to remain reactive to human triggering for the forecast period.
Snowpack Summary
Up to 30cm of snow has fallen in the last week, and resulting wind slabs continue to be sensitive to light inputs in upper elevation lee terrain. The persistent weak layer of surface hoar and facets buried in early January is now typically down 60-90 cm. The layer is slowly getting harder to human trigger in many areas, however, reports of whumpfing and recent large to very large avalanches around Golden indicate this layer is still very much a concern in the north of the region. In general, the lower snowpack below this layer is well settled and strong.
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.