Confidence
Fair - Forecast snowfall amounts are uncertain on Friday
Weather Forecast
Friday: Moderate to locally heavy snowfall / Strong southwest winds / Freezing level at 500mSaturday: Light snowfall becoming moderate to heavy overnight / Strong southwest winds / Freezing level at 800mSunday: Light snowfall / Strong southwest winds / Freezing level at surface
Avalanche Summary
A widespread avalanche cycle to size 2.5 was observed on Wednesday. The storm slabs failed on a variety of aspects and elevations. In at least one case, an avalanche was triggered remotely from a distance of 30m. This speaks to the highly touchy nature of the current instability.
Snowpack Summary
Between 60 and 100cm of recent snowfall overlies a medley of old surfaces which were buried on February 10th. These layers include: weak surface facets, surface hoar, a scoured crust, or any combination thereof. Professionals are expressing particular concern for the combination of buried facets on a crust being unusually reactive at treeline and below. Reports of whumphing and widespread avalanche activity further indicate a poor bond between the new snow and these old surfaces. Strong to extreme winds are shifting the new snow into deeper, reactive wind slabs in exposed terrain. With forecast warming and more snow on the way, the reactivity and destructive potential of the new storm slab will likely increase.The mid and lower snowpack are generally strong and well-settled. Basal facets and depth hoar are likely to exist in some parts of the region, but triggering has become unlikely.
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.