Friday's storm totals are expected to vary greatly across the region. Pay close attention to how much snow falls in your riding area as snowfall amounts and warming will drive the Avalanche Danger on Saturday.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Friday
Weather Forecast
The region may see up to 30cm of new snow on Friday night with extreme southwest winds. On Saturday morning expect overcast skies and lingering flurries with the possibility of sunny breaks in the afternoon. Another system will bring in up to 20cm of new snow and strong southerly winds between Saturday night and Sunday. On Monday a clearing trend is expected. The freezing level should hover around 1500m for most of the forecast period although there may be a brief spike to about 2000m on Saturday afternoon.
Avalanche Summary
Natural and artificially triggered storm slab avalanche activity in the size 2-3 range was reported from across the region on Wednesday. More recently, observations have been limited due to inclement weather. While recent storm accumulations will likely gain strength over the next few days, further storm loading on Friday night will spark a new round of destructive wind and storm slab avalanche activity on Saturday.
Snowpack Summary
Continued heavy snowfall and extreme southerly winds have formed deep and reactive storm slabs on lee and cross-loaded alpine and treeline features. On windward terrain, extensive scouring has been reported. Ongoing stormy weather has also encouraged extensive cornice growth. Recent storm totals (which vary from about 60cm to over 100cm) overlie a temperature crust, old wind slabs and spotty surface hoar. The mid and lower snowpack are generally strong and well-settled.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.