Next storm is expected to arrive late on Wednesday. If you're sick of seeing red, read the forecaster blog.
Confidence
Fair - Due to variable snowpack conditions
Weather Forecast
Wednesday: A Pacific Frontal system arriving in the afternoon will bring around 5-15cm new snow with continued strong SW winds. Freezing levels will be around 1000m. On Thursday, a stronger pulse of precipitation will bring 10-20cm new snow, again with strong SW winds. Freezing levels will go up to around 1500m, or even a little higher in the south of the region. On Friday, precipitation will continue but should become lighter. Freezing level again around 1500m.
Avalanche Summary
On Monday, several size 2-2.5 slabs released naturally (likely from wind-loading), which are suspected to have failed on the mid-February persistent weakness. A helicopter remotely triggered a size 1.5 slab, part of which stepped down to basal facets. A skier was also swept over a cliff in a size 1 slab which failed on the mid-Feb layer. On Sunday, a group of skiers triggered a size 3.5 slab 900m wide and 80-140cm deep on a north aspect in the southern Purcells. Late last week, large (size 2.5-3.5) human and explosive-triggered slabs were reported on all aspects, with crowns 40-120cm deep.
Snowpack Summary
80 to 160 cm storm snow now overlies the prominent surface hoar layer of mid-February. The storm snow is reacting readily to both natural and human triggers. The mid-February surface hoar layer is more stubborn and not reacting everywhere, but has regularly been producing large avalanches up to size 3.5, which indicates it is very much still alive and needs to be treated with the utmost respect. This layer is widespread, so defining safe zones based on elevation or aspect may not be the best idea right now. Of course, shallower snowpack areas are those where you are more likely to trigger it, as well as convex rolls, and rocky or uneven terrain features. If you know that a slope has already avalanched on that layer, it may be a better bet, although you still need to factor in the effect of recent storm snow amounts and whether reloading is an issue. Operators continue to monitor basal facets, especially in shallow, rocky areas, but with all the recent storm snow, the basal weakness has not been of undue concern recently.
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.
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.
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.