'Exceptionally dangerous': Major flooding, mudslide risk in parts of Southern Calif.

How wildfire burn scars make threat of flooding in LA more severe Mudslides, rockslides and rapid rising of waterways are possible in the region. ABC News In this Jan. 7, 2025, file photo, firefighters battle the Eaton Fire in strong winds as many homes burn, in Pasadena, Calif.David McNew/Getty Images, FILE In this Feb. 13, 2025, file photo, heavy rains created a mud filled debris flow sending cars down Tanoble Drive onto Mendocino Street in the Eaton fire burn area, in Altadena, Calif.Gina Ferazzi/Los Angeles Times via Getty Images, FILE Potentially catastrophic rain is heading toward Los Angeles -- a region already scarred by recent extreme weather and climate events, making it more vulnerable to the influx of water. Millions of people across California are on alert for flooding over the Christmas holiday, according to the National Weather Service. But Southern California will be under the bullseye of a prolonged, strong atmospheric river that will bring periods of heavy rain beginning Tuesday night and lasting into Thursday evening. Significant and widespread flooding caused by excessive rainfall is likely, with potential debris flow impacts across recent burn scars. The first round of rain -- beginning at about 9 p.m. Tuesday -- will be the strongest. Heavy rain is expected first over the Santa Barbara area before moving to the Los Angeles area around midnight. The rain over Los Angeles could continue until as late as 6 p.m. Wednesday, equating to 18 hours of moderate to heavy rain over the region on Christmas Eve. Rainfall rates may exceed 1 inch per hour at times, especially at higher elevations. Widespread rainfall totals over the 18-hour period are expected to reach between 3 inches and 7 inches, but some localized spots could see 9 inches or more. The month of December typically brings around 2 to 3 inches of rain to the region, on average, records show. The National Weather Service's Weather Prediction Center issued a rare “High Risk” (level 4 of 4) for excessive rainfall and flash flooding on Wednesday across portions of Southern California. This includes portions of Santa Barbara, Ventura, Los Angeles, and San Bernardino counties. The "High Risk" includes Los Angeles, Burbank, Altadena, Glendale, San Bernardino, Santa Clarita, and Thousand Oaks. Being under a “High Risk” is a rare occurrence. This risk is only issued about 4% of days, accounting for one-third of all flood-related fatalities and 80% of all flood-related damages, according to the National Weather Service. The Weather Prediction Center has issued a level 4 of 4 risk, a major risk, for excessive rainfall and flooding for Ojai, Thousand Oaks, Simi Valley, Santa Clarita, San Fernando, Glendale, West Hollywood, El Monte, San Bernardino and the Angeles National Forest. Los Angeles and Ventura counties were devastated by the Palisades and Eaton fires in January. Evacuation warnings are in effect from Tuesday to Thursday at 11 p.m. for the Palisades, Sunset and Hurst burn scar areas. Evacuation orders are in place for a select number of vulnerable properties. Los Angeles...

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