Southern California Faces ‘High Risk’ of Excessive Rain and Flooding

Parts of Southwest California on Sunday braced for heavy rains — potentially as much as an inch an hour — that could lead to life-threatening floods, officials said, prompting evacuation orders in some places and at least one school district to cancel classes for Monday.

The Weather Prediction Center issued a rare “high risk” prediction of excessive rain in an area that includes Santa Barbara, Ventura and Oxnard, saying eight or more inches of rain could fall in a 24-hour period.

The heavy rains pose flooding risks that could be “especially problematic” in areas previously scarred by wildfires, the center said.

On Saturday night, the National Weather Service said “rain totals still look to be very impressive” — of at least three to six inches across coastal areas and six to 12 inches for the foothills and mountains.

The storm is also expected to bring heavy mountain snowfall and widespread gusty winds, Eric Schoening, an emergency response specialist with the National Weather Service, said during a briefing on Saturday.

“The most significant rainfall totals for this event are expected across the central and southern coastline, including the Los Angeles and San Diego metro areas,” Mr. Schoening said.

“This damaging flooding will be a threat to lives and property,” he added. He said that the conditions were stemming from an atmospheric river event.

Mayor Karen Bass on Friday urged Los Angeles residents to monitor the storm and to pay attention to extreme weather warnings, adding, “We know the severe impact that weather can have on our communities.”

Santa Barbara County officials issued evacuation orders for properties in the Sycamore Creek area and along waterways associated with the Thomas, Cave and Alisal burn areas.

The governor’s office said it was preparing for the storm with 21 swift water rescue teams placed on standby and having the California State Guard ready for rapid deployment if called upon.

The Santa Barbara Unified School District announced on Friday that all schools and the district office will be closed on Monday because of the storm. Santa Barbara City College said on its website that its campuses will have remote instruction on Monday.

Forecasters posted a flood watch for Ventura, Santa Barbara and San Luis Obispo Counties from Saturday evening through Tuesday afternoon.

The National Weather Service posted a high wind warning for parts of Southwest California from Saturday evening through Sunday evening 10 p.m. local time.

Winds were expected to be 30 to 45 miles per hour, with damaging gusts of up to 65 m.p.h. Forecasters predicted that they could take down trees and utility lines, leading to power failures.

For many Californians, the days of officials standing on the edge of nearly empty reservoirs pleading with residents to save water or to let their lawns die may now feel like a lifetime ago.

But as 2022 came to an end, meteorologists began predicting that storms driven by atmospheric rivers would bring significant rain and snow, at last offering a respite from the drought that had plagued the state since 2020.

In the months that followed, Californians experienced the other side of the pendulum swing between weather extremes — swings that have become wider as climate change has made dry periods hotter and rainy cycles more intense.

All of it is more dangerous.

Huge, crashing waves destroyed piers on the coast. Outreach workers scrambled to ensure that people living on the streets of Los Angeles had shelter. Residents of Montecito, the seaside community favored by some of the world’s richest people, were forced to evacuate their homes five years after mudslides there killed 23 people.

In the Central Valley, a vast, almost mythic lake re-emerged. Rivers that in previous years had been ambling streams became dangerous torrents.

The winter and spring last year were so jarring and deadly, that when a hurricane appeared to be on track to hit Southern California in August, officials issued warnings that were dire.

What became Tropical Storm Hilary caused damage less catastrophic than had been anticipated. But now, as another atmospheric river barrels toward California, forecasters and officials are urging residents to take the warnings seriously.

John Keefe contributed reporting.