Regions
South Coast Inland.
The storm forecast for coastal regions is not expected to push very far inland initially. We are uncertain of new snow amounts on Tuesday.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Tuesday
Weather Forecast
Overnight: 3-5 cm of new snow above 1000 metres combined with moderate to strong westerly winds. Tuesday: 3-5 cm of new snow combined with strong westerly winds and daytime freezing levels around 1500 metres. Wednesday: 5-8 cm of new snow combined with moderate southwest winds and daytime freezing levels up to 1600 metres. Thursday: A brief ridge of high pressure should bring light winds and clearing skies, with periods of intense solar radiation.
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. No new reports of avalanches on Monday.
Snowpack Summary
Steady light snowfalls over last week deposited 25-45 cm of heavily wind affected new snow to the region. Periodic rises in freezing levels to 2000 metres or higher over the same time period have been setting up a series of crust layers (March 20, 22, 23) within the upper snowpack at lower elevations and on solar aspects. A more widespread thick rain crust (March 15) exists up to 2100m and is now buried approximately 45-70cm below the surface. In the north of the region, the February weak layers are 100-140 cm deep and include a buried surface hoar layer as well as a crust/facet layer that appear to be gaining strength. 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.