Patience and diligence may be required to resist venturing into complex terrain as the snowpack settles and adjusts to the recent load and warming.
Weather Forecast
SATURDAY: A mix of sun and cloud with isolated light flurries. Freezing levels around 1200m and light southwesterly winds. SUNDAY: A mix of sun and cloud and mainly dry with freezing levels dropping below valley bottoms and light variable winds. MONDAY: A mix of sun and cloud with isolated light flurries. Freezing levels in valley bottoms and light southwesterly winds.
Avalanche Summary
Reports from Thursday include natural wet slabs up to Size 2 at lower elevations, but observations were limited. On Sunday, a skier remotely trigger a size 1 avalanche on a NW aspect from 10m away. The slab was 60cm thick which suggests that it failed on the early January surface hoar layer. Natural loose avalanches up to size 2 were also reported from extreme terrain and did not trigger any slabs below. Widespread natural avalanche activity up to size 3 was reported on Friday and Saturday.
Snowpack Summary
Recent storm totals and freezing levels across the region have been highly variable with some areas receiving over 40mm of precipitation in the past few days with freezing levels spiking over 1700m, while others stayed relatively cool and dry. Weaknesses exist within and under this recent storm snow, which is particularly deep and touchy on wind-loaded slopes in alpine and exposed treeline areas, and bonding poorly to recently buried surface hoar, facets, and/or a crust at lower elevations and south aspects. The persistent weak layer of buried surface hoar, sun crusts, rime crusts and/or facets that was buried in early January is now down around a metre. The overlying slab remains primed for triggering and is especially touchy at and below treeline. The mid and lower snowpack below these layers is generally well-settled and strong, with any old weak layers considered dormant for now. Snowpack depths are variable and shallow snowpack areas may have weak facetted crystals near the ground.
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.