A powerful storm known as an atmospheric river swept over California on Thursday, soaking the state with rain and leaving a trail of damage that has become familiar to residents in recent years: fallen trees, flooded roads and snarled travel.

Though the storm was not expected to cause the kind of chaos that was sown by a succession of atmospheric rivers last winter, meteorologists warned residents to stay alert and be ready for an even bigger storm over the weekend.

“Not to sound alarmist, but it’s good to sort of prepare to hang out at home for a little bit,” said Rose Schoenfeld, a meteorologist with the National Weather Service in the Los Angeles area.

The current storm hit Northern California first, flooding roads on Wednesday and prompting the closure of streets and schools in rural communities. At least one person had to be rescued from a car that was taking on water in Sonoma County, and forecasters warned of big, dangerous waves on the coast.

The storm was potent enough to push San Francisco’s cumulative rainfall total above normal for the first time this season, according to a local meteorologist, Jan Null.