Cautious route-finding and conservative decisions is critical the next few days. Thursday to Friday's precipitation will be rain at lower elevations raising the potential for loose wet avalanches below treeline locations.
Weather Forecast
Thursday to Friday freezing level may be 2200m, rain in valley bottom with possibly 15cm of snow in higher elevations by Friday afternoon. Winds may shift Easterly on Friday afternoon with a second pulse of precipitation. Possibly a slight cooling trend on Saturday.
Snowpack Summary
Good skiing between 1900-2400m in sheltered areas. Wind-slab along lee ridge-lines and cross-loaded gully features from strong SW winds. Mid-pack bridging basal weakness. Lower snowpack is weak with a combination of facets, Nov rain crust and depth hoar. Below tree line a supportive 20cm melt freeze crust sits above a weak facet layer to ground.
Avalanche Summary
Helicopter flight from Jasper to Sunwapta Resort to Maligne. No new avalanches noted on this flight and visibility was good but very windy at ridge-tops. Tuesday's Bald Hill patrol also did not note any new avalanches. Previous cornice and wind-slab failures have triggered the deep persistent slab resulting large full path avalanches.
Confidence
Freezing levels are uncertain
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.