Another rain event is heading to fire-weary Los Angeles next week, and although this precipitation will provide a helpful dampening of dry brush, forecasters say it is unlikely to be heavy enough to put an end to the most destructive fire season in the county’s modern history.
The National Weather Service is forecasting a minor to moderate rain event in Los Angeles and Ventura counties next week from Tuesday through Thursday, with a quarter of an inch to an inch of rain expected. Rainfall amounts are predicted to be higher in the mountains and the hills, potentially accumulating from 1 to 2 inches, said weather service meteorologist Lisa Phillips.
The upcoming low pressure system follows last weekend’s stormy weather, which brought rainfall totals of half an inch to an inch across the county.
“To end fire season, we need about 2 inches for lower elevations and 4 inches for mountain areas,” Phillips said. “The first storm was not enough to do that, and it’s not looking like we are going to get enough with this upcoming one to do that either.”
Next week’s rains will still put a damper on fire danger by wetting vegetation and grass, she said. However, if offshore winds return and rainfall does not continue, that vegetation can dry up fairly quickly, she cautioned.
A third rain event could help push the county’s rainfall totals into the range necessary to end fire season, she said. But meteorologists don’t yet know whether such a system is in the works.
Although the wet weather is welcome, it does bring the danger of mudslides and flooding in areas charred by the massive Eaton and Palisades fires.
When rain falls at a rate of half an inch or more an hour, water can start flowing on the surface downhill instead of soaking into the ground and can begin to pick up rocks and debris. Burn scars are at particular risk because intense heat can make soil water-repellent, while the loss of vegetation can mean there aren’t enough roots to hold the soil in place.
Last weekend’s rainfall caused minor slides and flooding in the Palisades burn area, prompting the closure of Topanga Canyon Boulevard. But the upcoming rain event is expected to pose less of a risk.
“The last system was a really cold low-pressure system, and because it was cold, it brought a thunderstorm and convective shower that brought the higher rate of rainfall, which matters for triggering the debris flows,” Phillips said. “Because this system is warmer, that is probably not going to be as much of an issue.”
Although the weather in Los Angeles should remain dry on Saturday and Sunday, precipitation is expected over the weekend for the Central Coast and Northern California.
An atmospheric river is forecast to bring 1 to 3 inches of rain to the San Francisco area from Friday through Sunday and a dumping of snow in the Sierra mountains.
Meanwhile, San Luis Obispo County will see scattered showers with about a quarter of an inch of rain likely over the weekend, according to the weather service.
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