SAN FRANCISCO – Twin storms were forecast to batter California this week, the second one likely to provide the latest of a dozen atmospheric rivers to deluge the state in recent months.

The National Weather Service forecast periods of heavy rain and snowfall for the Sierra Nevada with wind gusts reaching 50 mph over the next few days.

“After a tranquil Saturday, active weather is expected to overspread much of the West,” the weather service warned.

The first storm had already begun ushering Pacific moisture into California on Sunday and was forecast to spread north quickly up the Pacific Northwest.

AccuWeather meteorologists warn that twin storms could deliver “significant” precipitation to Northern California before sweeping down to the southern part of the state.

“Any vigorous downpours could further exacerbate river flooding concerns in Northern California,” AccuWeather meteorologist La Troy Thornton said.

The second storm, arriving Tuesday, will likely include characteristics of an atmospheric river – a long, flowing region of the atmosphere that carries water vapor through the sky. AccuWeather said that storm will bring even heavier rain and mountain snow into Wednesday.

The series of storms battering California since late December have caused flooding in several locations, collapsed roofs in mountain communities overwhelmed by acres of snow and left thousands without power. But the storms also pulled most of the state out of a brutal three-year drought.

Only one-third of California remains under a drought advisory, most of in the least-concerning “moderate” category. In mid-December, 98% of the state was in some form of drought, the vast majority of it at least in the “severe” category.   

STORMS SWEEP CENTRAL US:Blizzard conditions possible

Developments:

►The second storm is likely to focus on Southern California, the ample availability of moisture sending rainfall amounts skyrocketing, AccuWeather said.

►Heavy rain is expected to affect the Los Angeles area Tuesday, and widespread flooding is possible. As of March 18, downtown Los Angeles has picked up 24.06 inches of rain since November, more than twice its normal total for the date.