KCRA reports that more than 270,000 California residents experienced a second round of rolling blackouts on Saturday.
California ISO declared a Stage 3 Electrical Emergency around 6:28 p.m. due to increased demand, as well as the loss of a 470-megawatt power plant. They also cite the loss of nearly 1,000 megawatts of wind power.
Update (with comment by Terry): When you retire increasing amounts of traditional thermal generation (i.e., coal) and increase usage of renewables, things start to get volatile. Welcome to the new normal.