Forecast snowfall amounts for Sunday night and Monday vary greatly across the region. Pay close attention to how much snow falls in your area, and be prepared to back off to simple terrain.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Monday
Weather Forecast
In most areas 8-15cm of snow is expected to fall between Sunday night and Monday afternoon. Another 10cm may fall on Monday night. Generally overcast skies and light flurries are forecast for Tuesday and Wednesday. Ridgetop winds will be moderate to strong from the southwest on Sunday night and Monday, and then become light on Tuesday and Wednesday. Freezing levels will hover around 1400m on Monday and Tuesday, and then drop to about 1200m by Wednesday.
Avalanche Summary
Observations were limited on Saturday, although a size 1.5 natural wind slab avalanche was observed near the Hurley Road on west aspect at treeline. New snow and wind on Sunday and Monday will encourage new wind slab activity at higher elevations while rain will promote a round of loose wet avalanche activity below treeline.
Snowpack Summary
New snow and moderate winds on Sunday and Monday will form new wind slabs at higher elevations. Below treeline, rain will saturate the upper snowpack. The new snow will overlie a sun crust on sun-exposed slopes, dry settled powder on shady slopes, and pockets of fresh wind slab in lee and cross-loaded terrain near ridge crests. Below the new snow the snowpack is strong and well-settled throughout with no notable persistent weaknesses. Cornices are reported to be large and fragile.
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.