There have been a few recent close calls in the north of the region near Golden. Very large human-triggered avalanches have been reported over the past few days. Conservative terrain selection remains critical.
Weather Forecast
On Wednesday evening, the first of 2 organized fronts will move through the region bringing 3-5cm of new snow and strong southwest winds. Thursday will see mainly overcast skies and continued strong ridgetop winds. By Friday evening, the second front will pass through the region. Expect another 5-10cm of snow and strong southwest winds. Freezing levels should remain at valley bottom for Wednesday and Thursday, and then rise to about 1500m for Friday.
Avalanche Summary
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. According to the report, 4 people were involved in the incident; however, all of the party member survived. Hats off to the sledders who responded to the incident in a calm and organized manner. Check-out the great Mountain Information Network report for details. 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. Nobody was injured in the event. On Monday, a size 2 wind slab was accidentally triggered by a skier in the backcountry around Golden. The individual was carried to the bottom of the slope, but was not buried or injured. Destructive persistent slabs are expected to remain reactive to human triggering for the forecast period.
Snowpack Summary
30-60cm of snow fell 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 in the Golden area 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.