SAN FRANCISCO — Despite the potential for flooding and mudslides, storms moving toward California were welcome news for a state suffering from a severe drought. But officials warned against reverting to old water-use habits.

As the first of the storms drenched the state on Tuesday, authorities cautioned that even the wettest of winters can’t replenish depleted reservoirs and aquifers unless everyone keeps pitching in.

California’s water deficit is so deep after four years of drought that a “steady parade of storms” like these will be needed for years to come, said Mike Anderson, climatologist for the state’s Department of Water Resources.

“We’re at least on a good trajectory,” he said. “We’ve got to keep it going.”

The current El Nino — a natural warming of the central Pacific Ocean that interacts with the atmosphere and changes weather worldwide — has tied 1997-1998 as the strongest on record, the National Oceanic and Atmospheric Administration’s Climate Prediction Center said, citing statistics that go back to 1950.

El Ninos usually bring heavy rains to California, although it remains to be seen whether people should expect anything like a repeat of 1997 and 1998, when storms killed 17 people, wiped out crops, washed out highways and pushed houses down hillsides.

“Darth Nino may finally have California in its sights,” said Jeff Masters, meteorology director of the private Weather Underground.