Despite the moderate rating the forecasters do not have much confidence in this snowpack. The spatial variability and shallow nature adds to the complexity. There is a low probability of triggering but severe consequences if you get it wrong.
Weather Forecast
Expect Monday night light flurries and -9. Tuesday will be freezing level of 2300m and variable clouds. A good overnight freeze Tuesday night and Northerly light winds. Wednesday and Thursday night there will be no freeze hovering around 2300m. Wednesday-Thursday will be very warm, sunny, and continued light North winds.
Snowpack Summary
Cold overnight temps and warming by midday is creating spring like snowpack and surface crusts. Significant variation in snowpack depth through-out the forecast area but generally shallow and below threshold in valley bottoms. Weak basal depth hoar exists. Maligne/Whistler creek areas less snowpack and higher spatial variability.
Avalanche Summary
Shooting cracks in the Maligne lake Bald Hills flats a result of surface crust over weak facets and shallow conditions. Loose wet slides on solar aspects in the south end of the park occurred on Friday with high temperatures. Saturday observed size 2.5 on SW'ly aspect near the Boundary and large serac collapse on the north glacier of Mt. Athabasca.
Confidence
Freezing levels are uncertain on Wednesday
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.
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.
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.