An ‘atmospheric river’ will dump rain on SoCal. What? 


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Summary

Major storm impact

A large storm is moving into Southern California and is expected to bring several inches of rain.

Weather hazards

Authorities have issued evacuation orders for several Los Angeles areas due to risks such as mudslides, which are heightened by recent wildfires that have made the terrain more vulnerable.

Potential end of fire season

According to Ryan Kittell of the National Weather Service, if the expected rainfall occurs, it could bring Southern California close to the end of its fire season.


Full story

A major storm moving into Southern California is expected to bring several inches of rain and some significant issues. It follows the massive wildfires that scalded parts of the area earlier this year.

Storm on the way

The storm is expected to move into SoCal Thursday night or Friday morning and stick around through the weekend.

“It’s that atmospheric river, that extra moisture that’s coming in that’s going to make this a really big rain event,” Alex Cheney, a SoCal meteorologist, told Straight Arrow News. “Southern California hasn’t had a storm like this since probably the beginning of the year.”

Downtown Los Angeles is expected to get more than two inches of rain, while some areas could see up to eight inches.

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What exactly is an atmospheric river that’s bringing all this wet weather?

“It’s basically just a movement of air pushing along moisture,” Cheney said.

That air comes in from the Pacific Ocean due to westerly winds.

“That’s why, when you fly from the West Coast to the East Coast, it’s faster than the East to the West,” Cheney said.

It brings ocean moisture, combining it with colder air coming in from the North.

“You need the combination of moisture and a cold air mass to be able to create rain,” Cheney said.

This weekend may also just be the beginning of some serious rainfall.

“It looks like there’s another system,” Cheney said. “We’ll get a break, Monday, Tuesday, then another one for the middle of next week. So gonna be a rainy 10 days or so for Southern California.”

Safety concerns

Evacuation orders for several areas around Los Angeles went into effect Thursday night and will remain in effect until Sunday morning because the rain poses several threats, including mudslides.

“In the LA area, you got a lot of hillsides that can come down really quickly [and] cliffs all the way up and down the coast,” Cheney said.

Mudslides are a major concern because the fires that loosened the terrain and removed vegetation make the terrain more susceptible to them.

Those fires are also a concern in this storm.

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Atmospheric rivers form when moisture-rich ocean air is intensified and steered by a jet stream towards land, where it condenses into heavy rain or snow.

“Who knows what toxic crap is just sitting on those lots?” Cheney said. “I know they cleaned a lot of them, but I don’t think they’ve gotten all of them.”

Cheney said that rain can cause “really dangerous” toxic runoffs, so people should pay attention to evacuation warnings.

“People really do need to heed those warnings because they’re trying to save your life,” Cheney said. “So, if you hear about something, if it pops on the TV, just stay vigilant over the next few days.”

There’s also one other issue Cheney pointed to when it comes to rain in SoCal, which doesn’t happen often.

“People don’t know how to drive in the rain,” Cheney said. “That’s not my meteorological opinion; that’s just me as a person. People forget how to drive in the rain.”

Several road closures will go into effect this weekend due to unsafe driving conditions, including a nearly 4-mile stretch of the Pacific Coast Highway.

End of fire season?

One positive some experts pointed to is that this rain could spell the end of fire season in SoCal.

“If we do end up getting the rainfall that we expect, this will certainly get us close to the end of the fire season,” Ryan Kittell, a meteorologist with the National Weather Service, told the LA Times.

Last year, SoCal experienced a record-breaking dry spell that left many areas vulnerable to fire. The ensuing Eaton and Palisades fires were among the deadliest and most destructive in state history.

Significant rainfall is often looked at as a counter to Santa Ana winds, which are a major factor in spreading wildfires.

Cole Lauterbach contributed to this report.
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Why this story matters

A major storm is forecasted to bring heavy rain and risks of mudslides to Southern California, posing safety concerns for communities, especially in areas affected by recent wildfires and potentially marking the end of the local fire season.

Storm impacts

The anticipated heavy rainfall may result in flooding, hazardous driving conditions and mudslides, particularly in regions already destabilized by wildfires, affecting public safety and local infrastructure.

Wildfire aftermath

According to meteorologists, recent wildfires have left hillsides vulnerable to mudslides and toxic runoff, increasing risks to health and property during heavy rain events.

Fire season ending

Experts such as National Weather Service meteorologist Ryan Kittell state that significant rainfall could help bring an end to the fire season, reducing the threat of future fires in the region.

SAN provides
Unbiased. Straight Facts.

Don’t just take our word for it.


Certified balanced reporting

According to media bias experts at AllSides

AllSides Certified Balanced May 2025

Transparent and credible

Awarded a perfect reliability rating from NewsGuard

100/100

Welcome back to trustworthy journalism.

Find out more

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