A powerful winter storm is lashing Southern California, with coastal communities bracing for multiple months’ worth of rain in just a few days, while areas charred by wildfires face the risk of mudslides.
“Lives and property are in great danger,” the US Weather Prediction Center said in a forecast early Wednesday. “Severe, widespread flash flooding is expected.”
The historic storm, which will pummel the region over the Christmas holiday until Friday, has prompted some evacuations in Los Angeles County and could bring road closures, airport delays and flight cancellations, officials said.
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.”
Related: California Hit With Powerful Storms Just as Holiday Travel Ramps Up
A combination of factors is making it a once in five-to-ten 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.”
Coastal regions of Southern California will receive multiple months’ worth of rain in a span of one to three days, according to AccuWeather.
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 up to 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.
Up in the mountains, the atmospheric river was welcome at area ski resorts as it brought massive amounts of snow. Mammoth Mountain expected up to 23 inches (58 centimeters) of total daytime snow accumulation on Wednesday, according to its website.
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