Atmospheric River Brings Heavy Rain and Flood Risks to Southern California

LOS ANGELES, CA — Evacuation warnings were issued across Los Angeles County Thursday evening as an atmospheric river approached Southern California, potentially ending fire season while increasing risks of flooding and mudslides.

Forecasters predict that downtown L.A. could see 2.62 inches of rain from Friday morning through Sunday, according to the National Weather Service. This would mark L.A.’s wettest November in 40 years, with some models estimating up to 4.81 inches of rain during this period.

On Saturday, the most significant risks arise, with meteorologist Ryan Kittell warning of potential flash flooding and debris flows. “The main message is that there’s still a pretty substantial potential for heavy rain over parts of our area,” Kittell said.

Debris flows can occur when heavy rain combines with mud and debris, which can travel down hillsides with destructive force. Kittell noted that this rainfall could help bring the current fire season to an end, stating, “If we do end up getting the rainfall that we expect, this will certainly get us close to the end of the fire season.”

Last year, Southern California faced a significant fire season that left vegetation primed to burn. The current outlook is in stark contrast, with meteorologists indicating that Southern California needs 3 to 4 inches of rain in lower elevations to effectively conclude fire season.

By contrast, parts of L.A. County are expected to receive varying rainfall amounts, including Long Beach with 2.38 inches, Santa Clarita with 2.77 inches, and Santa Barbara potentially up to 4.21 inches.

The storm could bring peak rainfall rates of 0.75 to 1.25 inches per hour during Saturday’s heaviest rainfall. Kittell explained that this intensity could trigger mud and debris flows, particularly in areas impacted by recent wildfires.

Forecasters have placed an emphasis on the need for residents to take precautions during the storm. “If you hear thunder or see lightning, just go inside,” Kittell advised. “Stay away from the windows, and you should be fine.”

Road closures, such as Topanga Canyon Boulevard between Pacific Coast Highway and Grand View Drive, have already been announced in anticipation of the storm.

While Southern California is bracing for the storm, it remains unclear how intense it will be, as Kittell noted the unpredictability of the storm’s path. “We can’t completely discount this thing pulling off the coast a little bit and resulting in less rain,” he said.

The storm is expected to arrive in Southern California after impacting the San Francisco Bay Area. Rainfall began lightly Friday morning, with an increase in intensity expected as the weekend approaches.