Although the trend shows improvement the potential for triggering an avalanche is greatest at higher elevations due to recent heavy snowfall and strong winds.
Weather Forecast
A ridge of high pressure will build over BC resulting in much drier and cooler weather for the next few days. Most areas should see a mix of sun and cloud with slight chance of the odd flurry. Freezing levels should gradually drop to 500-1000 m on Saturday and to valley bottom for Sunday and Monday. Winds ease off and become light and variable.
Avalanche Summary
Recent observations are limited from the region but there was a report of a size 2.5 explosive controlled wind slab on Thursday. This slide likely failed on weak layer buried in early December but appeared to step down to the early November crust. On Wednesday, one observer from the McMurdo Hut southwest of Golden reported seeing numerous avalanche crown lines and significant debris, particularly from alpine terrain. Natural activity should taper off this weekend but there may be lingering potential for triggering fresh wind or storm slabs higher in the alpine.
Snowpack Summary
The snow surface likely consists of moist/wet snow or a melt-freeze crust up to 2000-2200 m. Above this elevation there could be up to 40 cm of dense storm snow, which has probably been blasted around by strong southerly winds. In the Golden area a weak layer of surface hoar or facetted snow can be found under the storm snow. The mid pack consists of settled snow, facets, and melt-freeze crusts (primarily lower elevations). The mid-November weak layer (surface hoar, facets, and/or a crust) is buried 60-80 cm deep. Below this you will likely find a thick layer of sugary facets sitting on a solid rain crust from early November. The early November crust/facet layer did become reactive near Golden this week.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.