A so-called "atmospheric river of rain" began falling on Northern California on Friday, bringing worries about flash floods, high winds and mudslides but offering little relief to a state that has been left parched by several years of drought. The storm, also known as a "Pineapple Express" because it develops from a ribbon of moist air moving across the Pacific Ocean, was forecast to dump as much as 10 inches (25 cm) of rain in coastal mountains.
National Weather Service meteorologist Austin Cross said more than three inches (7.5 cm) of rain had been already recorded in the hills of western Sonoma County by early Friday afternoon. Fire crews responded to flooding in Siskiyou County, near the Oregon border, placing sandbags to protect homes and minor mudslides were reported in Washington state. Flash flood advisories were also issued for Sonoma, Napa and Marin counties in Northern California.
High winds caused more than 80 flights be cancelled and hundreds more delayed at San Francisco International Airport, knocked down trees and caused scattered power outages. According to Pacific Gas and Electric, more than 114,000 homes and businesses lost power, although the majority of them had been restored by late-afternoon. Cross said heavy rains were expected to fall into Friday night and again on Sunday after a brief lull on Saturday. Forecasters say that while the soaking would provide some relief to the drought-stricken state, it was not expected to make a significant impact, in part because the warm weather system would not add to mountain snowpacks.