Regions
South Coast Inland.
Huge variation exists between north and southern parts of the region. Cornices and deep weak layers remain a concern in the north.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
TUESDAY: Mix of sun and clouds. No new precipitation. Freezing level near 1800m but Treeline and Alpine temperatures a few degrees above freezing. Light east wind.WEDNESDAY: Increasing clouds with possibility of precipitation starting in the afternoon. Accumulations of trace to 10 cm. Treeline temperatures near zero with freezing level near 1500m. Light to moderate east wind.THURSDAY: Cloudy with periods of snow. Trace to 10cm or even 15cm of new snow. Treeline and alpine temperatures near or slightly below freezing. Mod southwest wind.
Avalanche Summary
Reports of a few avalanches were received Monday: an couple of accidentally triggered size 1 to 2 storm slabs near Pemberton and Birkenhead. As well as a size 2.5 cornice triggered avalanche near Birkenhead.
Snowpack Summary
Anywhere from 15-25cm of new snow is sitting on a widespread melt-freeze crust that exists on all aspects and elevations except for high elevation north facing terrain. Previous moderate winds from the south formed wind slabs in the alpine and added load to cornices. Cornices remain but windslabs have likely bonded. On sun exposed slopes and at lower elevations, several crusts likely exist in the upper snowpack which are generally well bonded. Both the mid February persistent weak layers and November deep persistent weak layer remain reactive to heavy loads (cornice falls and/or large explosives triggers) at upper elevations in the northern part of the region near Duffey and Birkenhead Lakes.
Problems
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.
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.