Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Saturday: Expect an unsettled day, with mostly cloudy skies and intermittent flurries. Accumulations up to 5cm are possible with upslope areas receiving brief, intense snowfalls yielding deeper localized deposits. Areas further inland (Coquihalla/Allison Pass) may see more intense precipitation. Alpine temperatures should remain cool at around -6 with light westerly winds.Sunday: We should see a mix of sun and cloud, with a chance of isolated flurries. Alpine temperatures should reach around -8 with light northeasterly winds.Monday: Expect a continued clearing trend with scattered clouds, alpine temperatures reaching -6 and light northeasterly winds.
Avalanche Summary
Avalanche observations have been limited in the last few days; however, 2 explosives controlled size 2.5 slab avalanches were reported on Wednesday from the Duffey Lake area. They occurred on a north facing alpine slope and ran 1000-1400m.
Snowpack Summary
Up to 10cm of new snow has fallen at higher elevations. This overlies Wednesday's moderate to locally heavy amounts. At lower elevations rain continues to saturate the snowpack. The previous storm was accompanied by moderate to strong south/southwest winds which left variable snow distribution in exposed areas near ridgetop, with dense wind slabs forming in lee and cross-loaded features. Up to 75cm below the surface you will likely find a melt-freeze crust from last week's sunny weather. At the same interface, you may also find spotty surface hoar on some high, north facing slopes.Cornices are huge!
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.