Significant snowfall is expected for the Columbia Icefield area - conservative terrain choices are advised until the snow has a chance to stabilize.
Weather Forecast
Weather models show the Columbia Icefield area receiving steady snowfall for the weekend, with up to 25cm total by Sunday night. Winds should remain light SW below 2000m, but will be gusting in the strong range (SW-NW) in the alpine. Temps remaining cool and freezing levels below 1300m.
Snowpack Summary
Windslabs on lee aspects (NE) of exposed ridgecrests above treeline are covered by 5-10cm of new snow. New snow is sitting on previous temperature crusts below 2100m and on sun crust on solar aspects. Cornices are big and heavy, and several natural cornice falls have been observed in the past few days. Melt freeze crust carries well in AM.
Avalanche Summary
No new avalanches observed today, but several large cornice failures reported in the past 48hrs. Of note, several of these cornice falls did trigger deep persistent slabs with crown fracture depths of up to 1m, and some were observed to have triggered more recent storm/wind slabs with a depth of 10-40cm.
Confidence
Intensity of incoming weather systems is uncertain
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.