Thursday may literally be 'The Calm Before the Storm(s)'. It looks like a wet and warm weekend ahead.
Weather Forecast
Synopsis: A series of frontal systems will affect the south coast over the next few days. The first and weakest system grazes the region tonight bringing light amounts of snow (5-10 cm) and relatively cool temperatures (freezing level around 1000-1400 m). The next, much stronger system dumps heavy snow/rain beginning on Thursday night maybe 20-40 mm. The freezing level shoots to 2000-2300 m with strong SW winds. Another wet and warm pulse should arrive sometime on Saturday bringing heavy rain and freezing levels up to 2500 m. Yikes!
Avalanche Summary
Recent avalanche activity progressed from a limited avalanche cycle on Saturday and Sunday (mainly from wind loaded terrain), to several explosive and rider triggered avalanches up to size 2 on Monday and Tuesday. Conditions will start to change heading into the weekend. Warm temperatures and rain could tip off another round of wet avalanche activity by Friday and/or Saturday.
Snowpack Summary
Up to 50 cm of settled storm snow sits on a hard crust and/or surface hoar layer. Previous strong W-SW winds redistributed snow in exposed terrain creating deep and dense wind slabs in lee features. The new snow seems to be bonding well to the crust, which is most pronounced between about 1500 m and 2200 m. The distribution of the surface hoar seems spotty across the region, but some operators found it to be widespread in their tenure before it was buried. Deeper snowpack weaknesses have fallen off the radar, but they could be reawakened with a very heavy load (like a cornice fall or wind slab) in the wrong spot (like a thin snowpack area).
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.