We're expecting a return to winter conditions heading into the weekend. Choose conservative routes until the weather improves and the snow has a chance to stabilize.
Weather Forecast
Synopsis: A series of frontal systems will affect the South Coast over the next few days bringing steady precipitation and gradual cooling to near seasonal temperatures. Tonight and Friday: Moderate to locally heavy precipitation – 10-15 cm overnight and another 15-20 cm during the day. The snow line should drop from to around 1400 m by the morning. Winds are moderate from the southwest. Saturday: Expect another 5-10 cm, mainly in the morning. The freezing level continues to drop to around 1200 m and winds remain moderate from the southwest. Sunday: Most likely a drier day but we should still see mainly cloudy skies and flurries. The daytime freezing level hovers around 1200-1400 m.
Avalanche Summary
Observations were limited on Tuesday and Wednesday. Previous reports were primarily loose wet sluffs up to size 2 on solar aspects and isolated cornice failures.
Snowpack Summary
New snow may not initially bond well to the previous snow surface, which potentially includes a melt-freeze crust, moist or wet snow, or pockets of surface hoar. Also, expect pockets of wind slab to form in exposed lee terrain in the alpine as winds pick up on Thursday night. The upper snowpack at lower elevations has become isothermal from recent warm temperatures. Adding rain to this on Friday could trigger loose wet sluffs or wet slabs in steep terrain. Cornices are very large and could pop off with continued mild temperatures. A layer of surface hoar (buried on March 11; now down about 60 cm) is still being observed in some locations. Triggering this layer has become unlikely, and would most likely require a large trigger or from a thin snowpack zone. Mid and lower snowpack layers are well bonded.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.