Weather Forecast
Synopsis: A ridge of high pressure off the coast of BC should maintain mostly dry conditions and sunny skies through the weekend and into next week. A weak disturbance sliding south through Alberta on Saturday could spread more cloud with a slight chance of flurries. The freezing level should remain near valley bottom and 1400 m. Winds are generally light to moderate from the west-northwest.
Avalanche Summary
There is one new report of a size 1.5 slab avalanche from a steep south aspect in the alpine that appeared to involve the recent storm snow. There were also a few size 1 loose snow avalanches were reported running out of steep headwall features.
Snowpack Summary
Up to 15 cm of recent snowfall has been redistributed into dense or hard wind slabs at higher elevations from variable winds. These accumulations overlie old wind slabs in exposed areas, settled storm snow or spotty surface hoar in more sheltered terrain, and a crust on previously sun-exposed slopes. A variable interface (surface hoar/facets/sun crust) was buried on Jan 23 and is down about 20-40cm. In most locations it now appears to be well bonded. The lower snowpack is generally well-settled. Cornices in the region are reported to be well developed and loom over heavily used slopes. These cornices deserve our respect, especially with clear skies and warming forecast for the weekend.
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.