Large cornices are unstable and can trigger big avalanches if they fall. Avoid all terrain below cornices. Gauge how quickly the overnight crust breaks down during the day relative to increasing danger.
Weather Forecast
Weather predictions have been unreliable for precipitation. Thursday night may bring 12mm, rain below 1900m turning to 10-15cm of snow later with overnight freezing level dropping to 650m. Friday-Saturday will be sun, freezing level 2200m or higher by the afternoon. Winds will remain light below 2300m but may gust moderate above 2400m on Friday.
Snowpack Summary
The top 30cm of snow is moist or wet depending on aspect and elevation. Melt freeze crust up to 2500m on S aspects. Mid-pack is solid and bridging the weak base. The bottom 30cm of the snowpack consists of weak facets and depth hoar mixed around the Nov rain crust. Below 1500m there is no snow.
Avalanche Summary
Thursday's Icefields patrol noted three size 1.5 loose wet at 1800m on S aspect. Also noted, a couple of cornice triggered size 2.5 deep persistent avalanches running on ground on West aspects at 2500-2800m. The size 2.5's appeared to be around 48 hours old.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.