SANTA ROSA, Calif, Nov 21, (AP): A major storm pummeled Northern California with rain and snow on Wednesday night and threatened to cause flash flooding and rockslides in the latest wave of damaging weather to wash over the West Coast. The National Weather Service extended a flood watch into Saturday for areas north of San Francisco as the strongest atmospheric river - a large plume of moisture flowing onshore - that California and the Pacific Northwest has seen this season inundated the region.

The storm system unleashed winds the night before that left two people dead and hundreds of thousands without power in Washington state. Up to 16 inches of rain (about 41 centimeters) was forecast in Northern California and southwestern Oregon through Friday. By Wednesday evening, some areas in Northern California had experienced heavy rain, including Santa Rosa, which had seen about 5 inches (about 13 centimeters) within 24 hours, according to Marc Chenard, a meteorologist with the National Weather Service.

Dangerous flash flooding, rockslides and debris flows were possible, officials warned. About a dozen small landslides had struck in northern California in the last 24 hours, including one on Highway 281 on Wednesday morning that caused a vehicle crash, said Chenard. The National Weather Service in the Bay Area warned people that the atmospheric river was focused on the North Bay and to "expect heavy rain to continue tonight, Thursday into Friday.

This will result in mudslides, road closures.” The storm system, which first hit Tuesday, is considered a " bomb cyclone,” which occurs when a cyclone intensifies rapidly. A winter storm watch was in place for the northern Sierra Nevada above 3,500 feet (1,066 meters), where 15 inches (38 centimeters) of snow was possible over two days. Wind gusts could top 75 mph (121 kph) in mountain areas, forecasters said. The storm had already dumped more than a foot of snow along the Cascades by Wednesday evening, according to the National Weather Service.