California Braces for Powerful Atmospheric River This Week

LOS ANGELES, California — A fast-moving atmospheric river is set to impact California this week, bringing heavy rain and potential flooding risks, particularly in areas recently affected by wildfires. The storm will arrive in Northern California on Wednesday and is expected to sweep into Southern California by Thursday, lasting through Saturday.

Forecasters anticipate that downtown Los Angeles could receive significant rainfall, with predictions indicating this might be the heaviest rain seen in over a month. Rose Schoenfeld, a meteorologist with the National Weather Service in Oxnard, warned of potential flash flooding in burn scar areas. “A flood watch will be possible for burn scars,” she said.

While heavy rains pose a threat, they could also indicate the end of the autumn fire season. Rain in Northern California has already reduced fire danger, and this storm could similarly benefit Southern California. The weather service described the storm as “potentially significant,” with roadways likely to flood and risks of rockslides in canyon roads.

Rainfall estimates for the L.A. metro area suggest 1 to 2 inches along the coast and valleys, with higher amounts of 2 to 4 inches possible in mountain regions. Schoenfeld noted the urgency of preparations: “We’re looking at moderate to locally heavy rain rates with this system.” Specific areas, including Long Beach and Oxnard, could receive over an inch of rain.

In addition to rain, strong winds are also a concern, with gusts reaching up to 50 mph in some locations. Rainfall rates could exceed an inch per hour, especially in areas with recent burn scars, heightening the risk for debris flows.

The weather service noted that if rainfall trends remain consistent, a flood watch will likely be issued for vulnerable areas on Friday. While Los Angeles residents are not advised to avoid travel entirely, those living in flood-prone regions should exercise caution.

David Gomberg, an NWS fire program manager, commented on the potential impacts of the approaching storm. “It will take several weeks to fully assess the vegetation response, but the expected precipitation may significantly alter the fire season’s dynamics,” he explained.

The storm is predicted to bring cold temperatures as well, with downtown L.A. showing a drop from a high of 92 degrees earlier this week to a high of only 61 degrees by Friday.

Rain is expected to taper off by Friday afternoon, though more rain showers could return on Saturday, with uncertain amounts. “That Saturday precipitation amount is pretty uncertain,” said Schoenfeld, hinting at unpredictability with the storm’s progression.

Thunderstorms, small hail, and gusty winds are also possible across California during this system. In the San Francisco Bay Area, the heaviest rain is expected late Wednesday into Thursday, with widespread rainfall amounts of up to 2 inches likely in some regions.

In the Sierra Nevada, heavy snowfall will accompany the storm, with up to 18 inches expected in higher elevations, leading California Highway Patrol to require chains for crossings. A winter storm warning will be in effect from Thursday through Friday for several mountain regions.