Regions
South Coast Inland.
Warm temperatures combined with potential extended periods of sunshine may increase avalanche danger as the day progresses on Friday
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Friday
Weather Forecast
FRIDAY: Mix of sun and cloud / Light southwest wind / Alpine temperature -2 / Freezing level 1400mSATURDAY: Cloudy with sunny breaks and isolated flurries in the north. Flurries in the south, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -2 / Freezing level 1200mSUNDAY: Mix of sun, cloud and isolated flurries / Light to moderate west wind / Alpine temperature -3 / Freezing level 1300m
Avalanche Summary
Several thin wind and storm slab avalanches to size 1.5 in steep lee terrain were reported on Monday, Tuesday and Wednesday in the north of the region.
Snowpack Summary
Steady light snowfalls over the last week have accumulated 40-60cm of new snow in the region. Freezing levels to 2000m or higher and intermittent sun over the same time period created a variety of thin crust layers within the upper snowpack at lower elevations and on solar aspects. A thick rain crust forming in Mid-March up to the 2100m elevation is down 50-80cm 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.