Highly sensitive storm slabs are everywhere. Conservative terrain selection is essential for safe travel.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Thursday
Weather Forecast
Tuesday: Mainly cloudy with another 2-5cm of snow, moderate southerly winds and freezing levels around 1100m. Wednesday: A mix of sun and cloud but generally dry, light winds and freezing around 1000m. Thursday: As much as 15cm possible, but some areas may receive nothing. Strong southerly winds and freezing levels around 1200m.
Avalanche Summary
On Saturday, three human triggered avalanches were reported from north of the region. A ski cut on a northwest aspect at 1700m caused sluffing which subsequently triggered a size 1.5 slab avalanche which released on the early-January surface hoar. Two 30cm thick soft slab avalanches were ski cut in a northeast facing cross-loaded gulley feature at treeline. In the upper Lillooet, numerous recent natural dry loose avalanches up to Size 1.5 were observed below treeline. Subsequent avalanche control produced 25-45cm thick storm slab avalanches up to Size 2, running on the early January surface hoar.
Snowpack Summary
20-25cm of fresh storm snow has buried the recently formed mid-January surface hoar layer. Below that are the two early-January interfaces down 30-50cm which are separated by around 15cm of snow and both consist of a sun crust on steep solar aspects and a layer of surface hoar on sheltered and shady slopes. Moderate to strong southeast through southwest winds have been loading lee features at treeline and in the alpine. The mid and lower snowpack is generally strong, with the exception of shallow snowpack areas that may be more faceted.
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.