If the forecast precipitation falls as rain rather snow expect the avalanche danger to rise rapidly at low elevations.Road closures after mid day along the Maligne Lake Road and Icefields Parkway can be expected if we see significant rain.
Weather Forecast
A possibility of light rain at lower elevations and snow near treeline. Up to 30cm of new snow could fall by Saturday evening as cool easterly air is confronted by an upper elevation westerly flow. Valley bottom temperatures will warm during the day producing convective uplift and more snow. Glacial out flow will cool the valleys overnight.
Snowpack Summary
Below Treeline a supportive 15cm melt freeze crust provides temporary stability above a wet and unconsolidated snowpack. The crust thins with elevation and on slopes which are not South facing. By mid afternoon, or earlier on very hot days, this crust will melt and the avalanche danger will increase considerably. The base of the snowpack is weak.
Avalanche Summary
Avalanche activity will be at its greatest by mid afternoon or during rain events. During the morning a strong crust prevents natural avalanches. As the crust melts the danger increases. At that time avalanches up to size 2 can be expected. Falling cornices can trigger full snowpack slabs of size 3 from the alpine. Cool temps reduce the danger.
Confidence
Freezing levels are uncertain
Problems
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.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.