LOS ANGELES — A powerful storm with the potential for life-threatening flash flooding is moving onshore over California early Wednesday, threatening to be one of the wettest Christmas Eve-to-Christmas Day periods on record for Los Angeles.
“A dangerous scenario is unfolding,” the National Weather Service (NWS) warned early Wednesday.
The NWS’ Weather Prediction Center issued a rare Level 4 out of 4 “High Risk” of flash flooding for places just north of Los Angeles in Santa Clarita, Burbank and Glendale through Christmas morning.
Los Angeles itself is under a Level 3 flood threat, as the region, home to more than 12 million people, prepares for a widespread 3 to 5 inches of rain within a 24-hour period.
Flash flood warnings were issued early Wednesday across Santa Barbara and Ventura counties.
LA officials emphasized the severity of the flood threat on Tuesday, asking people to stay aware as they celebrate Christmas Eve and prepare for potential flash flood emergencies.
Cars move down Lake Avenue as heavy rain is set to arrive over the Christmas holiday on Tuesday, Dec. 23, in Altadena, California. Carlin Stiehl for NY Post
Workers service power lines as rain begins to fall on Tuesday in Altadena. Carlin Stiehl for NY Post
The NWS’ Weather Prediction Center issued a rare Level 4 out of 4 “High Risk” of flash flooding for places just north of Los Angeles in Santa Clarita, Burbank and Glendale through Christmas morning. FOX Weather
This comes after days of rain have saturated soils, creating prime conditions for dangerous flooding. Mudslides and debris slides are expected, according to the NWS.
The Los Angeles Fire Department has issued evacuation warnings for debris flows for several areas around burn scars from January’s wildfire disaster through 11 p.m. Thursday.
Ash from wildfires creates burn scars—a water-repellent coating that prevents the ground from absorbing water and causes the area to be predisposed to flash flooding and debris flows.
People near the Palisades and Eaton Fire burn scars were urged to take protective action earlier in the week.
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The Los Angeles County Department of Public Works distributed sandbags in Altadena and other vulnerable communities.
Visit the City of Los Angeles website for the latest on evacuation orders.
The FOX Forecast Center warns that as the system moves onshore, atmospheric instability will be high enough to trigger severe thunderstorms, some of which could even produce a tornado.
In addition to the heavy rain, this storm system could pack wind gusts up to 80 mph along the coast.
Wind Alerts have been issued for most of the California coast through Thursday.
A drainage tower stands in the Rubio Wash Debris Basin as heavy rain is set to arrive over the Christmas holiday on Dec. 23 in Altadena. Carlin Stiehl for NY Post
Workers apply a waterproof synthetic roof underlayment to a home in Altadena. Carlin Stiehl for NY Post
Clouds move over the San Gabriel Mountains on Dec. 23. Carlin Stiehl for NY Post
This comes after an atmospheric river soaked the region over the weekend and produced deadly flash floods in the northern part of the state.
The rain snarled holiday travel and could cause yet more delays Wednesday at San Francisco International and Los Angeles International Airport.
While the heaviest rainfall is expected Wednesday, a Level 2 out of 4 risk of flash flooding covers San Luis Obispo and extends across much of the Transverse Ranges north of Los Angeles through Thursday.
Flood Watches remain in effect for much of the entire state through Friday.
Sand bags are placed in front of a driveway to prevent debris flow at a home in Altadena. Carlin Stiehl for NY Post
A peacock perches atop a driveway fence in Altadena as a powerful storm is set to hit California. Carlin Stiehl for NY Post
“High Risk” flood threats are only issued on about 4% of days (including tropical and non-tropical events), but this risk category accounts for 39% of flood-related fatalities and 83% of flood-related damages in the continental US, according to research by Weather Prediction Center meteorologists.
Research shows that 6% of high-risk flood days have at least one fatality or injury, and 62% of such days have at least $1 million in damages.
This level of threat can produce impassable inundation in areas that have never flooded in the past.
The Los Angeles Fire Department has issued evacuation warnings for debris flows for several areas around burn scars from January’s wildfire disaster through 11 p.m. Thursday. FOX Weather
Meanwhile, those driving over the Sierras should expect mountain pass closures and hazardous travel conditions beginning Tuesday through Friday.
Feet of snow are expected to fall on the Sierras through the holiday week, with snow levels dropping to 5,000 feet.
Winter Weather Alerts have been issued for the Sierras through Friday.
Be sure to keep tabs on your FOX Weather app and any government-issued alerts from the NWS that will warn you of life-threatening flooding at your location.