Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
The timing and intensity of a series of fronts affecting the area is uncertain. The general picture is for the rest of the week to be stormy.Wednesday: Cloudy, with snow developing in the morning and continuing overnight. Freezing level around 1000m. Moderate to strong south-westerly winds. Thursday: Heavy snow. Moderate to strong south-easterly winds. Freezing level around 1500m.Friday: More snow. Freezing level falling to around 1000m.
Avalanche Summary
It's been an active week for avalanche activity and the cycle is expected to continue. On Monday, a skier was partially buried and two others escaped a size 2 slab on an east aspect at 1500m, which failed on a crust. Natural and skier-remote triggered avalanches to size 3 were also observed on a variety of aspects and elevations, some failing on the mid-February weakness. Crowns were up to 150cm deep. Every day of the last week, avalanches have been triggered either naturally, remotely or accidentally by backcountry travellers. Conditions are not expected to improve quickly.
Snowpack Summary
Stormy conditions are creating ever-deeper wind slabs and storm slabs. The upper snowpack is like a club sandwich with layers of new wind slab, storm snow layers of variable density, old moist snow and hard old wind slabs. Storm slabs or wind slabs may step down and trigger a deep weakness, formed in mid-February. On Monday, reports of avalanches failing on this layer naturally and with a remote trigger started coming in. Very large avalanches are possible, which could be remote-triggered, triggered mid-slope, and/or propagate into low-angled terrain.
Problems
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.
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.