California is grappling with the coldest air mass in three years as a major winter storm brings heavy snow, road closures, and power outages. Two Pacific storms will dump over three feet of snow in the Sierra Nevadas and heavy rain in lower areas like Los Angeles and San Diego, raising flood risks in fire-burned zones. The National Weather Service warned of "multi-day, very heavy snow totals of more than a foot" from southern Cascades to southern California and east into the Rockies. Up to 7 feet of snow is possible at high elevations near Yosemite. The Central Sierra Snow Lab near Donner Pass reported 28 inches of snow on Tuesday, with another 3 feet expected soon. I-80 is closed from Colfax to Nevada due to heavy snow. Several skiers went missing after an avalanche at Castle Peak; the Sierra Avalanche Center expects a "widespread natural avalanche cycle over the next 24 hours." Some ski resorts around Lake Tahoe have closed lifts, and Yosemite remains open with tire chain rules. However, cloudy weather may hide the famous February Firefall at Horsetail Fall, the park said. Storm effects reach beyond snow zones. Stanford University closed for two hours after a power outage caused by a PG&E transmission line issue. Coastal Highway 1 remains partly closed after a landslide. In Southern California, heavy snow could hit I-5 and I-14 corridors with strong winds up to 70 mph. Flood watches are active in Los Angeles, with evacuation warnings near recent fire burn areas including Palisades and Eaton. Floodwaters already affected parts of Los Angeles, even trapping a food delivery robot in West Hollywood. Authorities urge caution and readiness for possible evacuation orders.