A weak and variable snowpack from recent strong winds and cold temps warrants a cautious approach. Identify features of concern.
Weather Forecast
Sunday will be cloudy with sun and flurries, trace snow, -20 to -13 and NE light winds. Monday will be a mix of sun and cloud, no snow, -19 to -14, and light Westerly wind. Tuesday will be sun and cloud, -16 to -11, and light SW winds. Wednesday will be cloudy and flurries, a trace of snow, -15 to -8, with light SW winds.
Snowpack Summary
Wind slabs and extensive wind effect is found in open areas. Recent warm temps and solar effect will have created a crust on solar aspects below treeline. The upper snowpack is a 50 to 80 cm thick slab that sits on three weak layers in the mid-pack. The entire snowpack is faceted after two weeks of cold, dry weather.
Avalanche Summary
Friday's road patrol to Sunwapta noted one giant cornice failure, the size of a bus, with no initiation below. No other naturals were noted in this immediate area. On Wednesday, isolated large Na avalanches were observed. One windslab from a cross loaded pocket on a W aspect and one persistent slab on an E aspect.
Problems
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.
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.