The Summary
- Rain is in the forecast this weekend for Southern California.
- The rain could help firefighting efforts, but it also brings risks of mudslides, flash flooding and toxic runoff.
- California Gov. Gavin Newsom and Los Angeles Mayor Karen Bass said preparations are underway to address those threats.
Southern California is expected to see some much-needed rain this weekend, which could be a welcome respite for firefighters who have been fighting deadly wildfires in the Los Angeles area for almost three weeks.
However, the anticipated precipitation also increases the potential of hazardous runoff, flash flooding, and mudslides.
According to the National Weather Service, the San Gabriel Mountains might receive up to 1.5 inches of rain, while the majority of Los Angeles County could receive about half an inch beginning Saturday afternoon and perhaps continuing through Monday.
According to the meteorological service’s weekend forecast, there is also a 10–20% chance of thunderstorms, which can produce tiny hail and isolated, intense downpours with rainfall rates as high as 0.50 inches per hour.
The rain is expected to aid in the extinguishment of the fatal wildfires that have charred tens of thousands of acres in the counties of Ventura, Riverside, and Los Angeles. As of Thursday, the Palisades Fire, the biggest fire, which started on January 7th, was 72% contained.
Over the past eight months, Southern California has experienced unusually dry weather due to a protracted drought. Early May was the last time Los Angeles saw more than a tenth of an inch of precipitation.
However, the precipitation poses additional concerns even if it will probably help with firefighting efforts. Rainfall over these burn scars can more readily erode steep environments since freshly burned ground is usually less stable and has less vegetation to anchor soil. According to the U.S. Geological Survey, that can result in hazardous mudslides that can carry boulders and heavy woody debris, endangering human life and damaging properties and blocking drainage channels.
Earlier this month, there was a landslide in Pacific Palisades that damaged a house that had withstood the fires. As the rainy season intensifies, Los Angeles Fire Department officials said they anticipate landslides in the burn scars to be a serious worry.
Storms might deliver scattered, brief, heavy rain, which raises the danger of flash floods and carries a low but non-zero risk of debris flows over recent burn sites, according to the National Weather Service, even though this weekend’s prediction only calls for a 10% to 20% chance of thunderstorms.
In order to preserve burn scar sites, California will have sandbags, plastic sheeting, and other supplies on hand, Governor Gavin Newsom announced Wednesday.
“I instructed my departments and agencies to take immediate action to safeguard neighborhoods from potentially dangerous debris flows even before we saw rain on the horizon in Los Angeles,” Newsom said in a statement.
In order to filter runoff and protect streams from harmful contamination, he noted, silt fence and other physical obstacles would be employed.
Toxic ash containing dangerous materials like lead and asbestos is frequently found in the burned ruins of homes and neighborhoods. Hazardous chemicals from paint, electronics, automobiles, and other household objects can potentially be released during a fire. In regions that have recently burnt, post-wildfire rain can carry these harmful substances into streams, the ocean, and other waterways if proper safeguards are not in place.
L.A. Mayor Karen Bass posted on X on Tuesday that the city is acting aggressively in anticipation of wet weather. Toxins from burned areas are flowing into our water, beaches, and ocean, and crews are getting ready to stop it.
According to Bass, work is being done to erect strengthened barriers, use heavy machinery to clear fire debris, and collect and redirect rainfall into sewer systems.