Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
Watch for steep terrain where a cohesive slab sits over the weak facets of the lower snowpack. Human triggering is possible in these areas and we have seen several recent avalanches on these facets. Probe often or dig to find these spots.
Weather Forecast
The arctic ridge of high pressure has arrived and will dominate for the next few days. Dress warm!! Lows of near -30'C are expected with daytime highs reaching -18'C under clear skies with light winds from the north. It looks like the temperatures will start to moderate and rise slowly by Wednesday.
Snowpack Summary
The snowpack is mostly weak and facetted, with 15-25 cm of recent snow as the surface layer. Winds over the past week have created wind slabs in exposed areas, and in many places these wind slabs sit on a weak snowpack comprised of facets and depth hoar. A snow profile done Sunday in the Helen Shoulder area showed a very poor snowpack structure.
Avalanche Summary
Two size 2-2.5 natural avalanches in the Corral 1 and 2 paths, and a size 2 natural on Ptarmigan Peak observed Monday outside the Lake Louise ski resort. A recent size 2.5 avalanche was observed on the N side of Mt Burgess as well as a couple smaller slides on the SW aspect of Wapta Peak. All appear to be failing on the weak mid pack facets.
Confidence
Due to the number of field observations
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.