Southern California in ‘Great Danger’ from Christmas floods

About 10,700 customers in Los Angeles Department of Water and Power’s service territory were out of power Wednesday morning as a result of debris from the rainfall, according to a statement from the utility. Southern California Edison also reported some outages due to storm conditions.

The state has pre-positioned emergency response resources across the state, including 55 fire engines and 10 swiftwater rescue teams, to protect communities from the dangerous winter storms, according to a statement from Newsom.

The heavy rains threaten more extreme floods in Pacific Palisades and Altadena, communities in Los Angeles County that were devastated by massive wildfires nearly a year ago. The charred off vegetation makes the land impervious to soaking up the water, increasing the risk of landslides, mudslides and power outages.

It’s a risk that will persist when atmospheric rivers strike Southern California until the soil recovers and vegetation grows back.

“Those soils are still hydrophobic, which means that rain just runs off like it’s hitting hard dirt or concrete,” said Scott Kleebauer, a meteorologist at the Weather Prediction Center. “There are burn scars that have lasted for four or five years before you see any improvement.”

A combination of factors is making it a once in five-to-10-year weather event, he said.

A trough of low pressure that stretches across the Pacific Ocean is pushing wet air right up against the coastal mountains in Southern California, said Kleebauer. “It’s called the Pineapple Express because the moisture feed extends all the way back to Hawaii,” he said.

The wet air is hitting California at the perfect perpendicular angle for maximum rainfall. “You get this tropical moisture source forced into the mountains and then it just rains itself out,” he said. “This is impacting one of the biggest travel days of the whole year. That is definitely going to thwart plans for a lot of people.”

Peak rainfall in parts of the region is expected to reach as high as 1.5 inches (3.8 centimeters) per hour, according to the National Weather Service. The foothills and mountains south of Point Conception, which include parts of Los Angeles and Santa Barbara, are projected to receive as many as nine inches (25 centimeters) of rain by 10 p.m. local time on Christmas Eve. The rain will continue to pummel the area on Thursday, Christmas Day, and a total of 14 inches (35 centimeters) could soak the region by Friday.

Forecasters were also urging Californians to drive with care and never attempt to drive through flooded roadways. High winds were also whistling through the area, with one gust northwest of Los Angeles clocked at 82 miles per hour (132 kilometers per hour) according to the Weather Prediction Center.

Further north, the San Francisco Bay Area was at “marginal risk” of severe thunderstorms, the local arm of the National Weather Service said in a post on X. The primary concern there is wind gusts of 70 miles per hour or higher, with a 2% chance of waterspouts developing offshore and becoming tornadoes as they move onto land.

Up in the mountains, the atmospheric river was welcome at area ski resorts as it brought massive amounts of snow. Mammoth Mountain expected as many as 23 inches (58 centimeters) of total daytime snow accumulation on Wednesday, according to its website.