Regions
South Coast Inland.
Wind slabs and cornices are the main concerns right now. Carefully assess terrain before committing to bigger lines.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
We're looking at unsettled and variably wet spring weather through Thursday, with clearing and fine weather for Friday.WEDNESDAY: More wet snow (5-10cm) above 1600m and the potential for intense squalls (and thunderstorms). Winds moderate southerly.THURSDAY: Isolated flurries (5-10cm possible) with wet snow above 1500m. Winds light southwesterly.FRIDAY: Sunny with cloudy periods. Freezing level rising to 2100m. High temperatures to +4 Celsius. Winds light southerly. NOTE: The convective flurries which are common during this time of year can result in widely varying snowfall amounts throughout a region. These spring squalls routinely drop 20+ cm of snow in one valley while the adjacent drainage remains dry. For this reason, the distribution of avalanche problems associated with new snow, such as wind slabs, can vary greatly within a region.
Avalanche Summary
No new observed; however, deep persistent weak layers (including the November facet/crust combination) remain possible to trigger with large loads such as cornices. Loose wet avalanches are also possible below treeline where the temperatures have remained above freezing.
Snowpack Summary
This region received 7-10cm of snow above 1500m on Monday into Tuesday. It fell on light amounts of previous snow (10-20 cm over the long weekend) which settled into isolated stiff wind slabs in the immediate lee of exposed terrain features at treeline and above.Dry snow can still be found on north aspects above 1900m; however, moist (or crusty) snow can be found under the most recent snow on almost all south-facing slopes at all elevations.Cornices remain large in some areas and could trigger large avalanches when they fail (especially when warmed by the sun). The fatal accident near Lions Bay a week ago illustrates the danger of cornices breaking off, and the large avalanches they can trigger.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.