A “rather impressive system” is setting the stage for what could be California’s first atmospheric river storm of the season, the National Weather Service said Sunday. An atmospheric river carries water vapor from the tropics and, when it makes landfall, can bring a vast amount of rain and snow; in Oct. 2021, for instance, San Francisco got 750% more rainfall than an average year after a powerful atmospheric river passed through the region.
Because the movements of atmospheric river storms are difficult to predict, meteorologists are still refining the forecast. As of Sunday morning, “confidence is high” that northern parts of the North Bay “will be impacted by the strong atmospheric river beginning Wednesday, but these impacts could shift slightly southward closer to the SF Bay,” the weather service said.
Daniel Swain, a UCLA climate scientist, warned that forecasts are still uncertain. “Outcomes range from a major storm sequence (including flood risk) to nearly dry conditions, depending on trajectory,” he wrote on social media, adding that Southern California is likely to stay relatively dry in this storm in either scenario.
