Early season atmospheric river to bring significant rain next week to Southern California

PLAYA DEL REY, SEPTEMBER 29, 2023 - - RIDERS ON THE STORM - Bicyclists enjoy a nice ride on the beach bike trail before some possible rain over the weekend in Playa Del Rey on September 29, 2023. (Genaro Molina/Los Angeles Times)
Bicyclists ride on the beach bike trail in Playa del Rey earlier this year. (Genaro Molina/Los Angeles Times)

While strong winds remained a concern Thursday, meteorologists have their eye on a moisture-rich storm expected to bring significant rains to Southern California by the end of next week.

An atmospheric river system with a "decent moisture plume" is forecast to hit Southern California as early as Wednesday, and is expected to bring up to 4 inches of rain to some areas, said David Sweet, a meteorologist for the National Weather Service in Oxnard.

"We anticipate getting more than an inch, maybe as much as two inches" to much of the Los Angeles area, Sweet said. The mountains could see as much as 4 inches.

"It will certainly tamp down any fire threat that we're dealing with currently," Sweet said.

Read more: Bomb cyclone, atmospheric river, polar vortex: How our weather terminology has grown with recent wild storms

While the storm is still almost a week out, Sweet said models show slightly different timing and rain amounts for the system. But he said with confidence the "pineapple express" system will bring significant precipitation with some strong southerly winds. Rains are likely to be most significant Thursday and Friday next week.

But in the short term, officials are still warning about dangerous fire conditions in most L.A. County valleys and mountains, as well as a the Malibu coast, with a red flag warning still in effect through Thursday evening. Gusty Santa Ana winds up to 50 mph, along with low humidity, mean that any fire start could spread rapidly, the weather service warned.

Those winds are expected to die down by Friday, causing minor cooling, Sweet said. However, the offshore winds will have a slight resurgence over the weekend, though not to the point of further concern, he said.

"Those Santa Ana-type winds [this weekend] will boost our temperatures back up into the 80s," Sweet said.

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This story originally appeared in Los Angeles Times.