Regions
South Coast Inland.
A steady accumulation of snow over the past few days has gradually increased the avalanche danger at upper elevations
Confidence
Moderate - Forecast snowfall amounts are uncertain on Wednesday
Weather Forecast
WEDNESDAY: Flurries, accumulation 10-20cm Tuesday night through Wednesday / Moderate to strong southwest wind / Alpine temperature -2 / Freezing level 1400 m THURSDAY: Cloudy with sunny periods and isolated flurries / Light west wind / Alpine temperature -2 / Freezing level 1400mFRIDAY: Cloudy with isolated flurries / Light to moderate southwest wind / Alpine temperature -4 / Freezing level 1200m
Avalanche Summary
One report of a cornice collapse in the south of the region on Sunday that resulted in a slab avalanche; the size was not reported due to poor visibility. A few isolated thin wind slab avalanches were reported on Monday in the north of the region.
Snowpack Summary
Steady light snowfalls over last week accumulated 30-55cm of heavily wind affected new snow in the region. Freezing levels to 2000m or higher and intermittent sun over the same time period created a variety of crust layers within the upper snowpack at lower elevations and on solar aspects. A thick rain crust forming in Mid-March up to 2100m is down 45-70cm below the surface. In the north of the region, the February persistent weak layers may still be found and are down 100-140cm. They include a buried surface hoar layer as well as a crust/facet layer. In the southern parts of the region, the mid and lower snowpack are generally well settled and strong.
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.