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Atmospheric River Storm Front To Dump Heavy Rain On Southland Through Christmas Eve

LOS ANGELES (CBSLA) — Yet another atmospheric river storm was making its way into the Southland Thursday, bringing with it the risk of flooding and mudslides in wildfire burn areas.

Atmospheric River Storm Front To Dump Heavy Rain On Southland Through Christmas Eve
Sandbags in the Bond Fire burn area in Silverado Canyon in Orange County amid a storm. Dec. 23, 2021. (CBSLA)

Rain started out light Thursday morning, but was expected to get heavier across the region as the day went along, forecasters said.

"The heavier rain continues into the overnight hours, into early Friday morning. Now it's by Friday afternoon that we finally start to dry out," Biston said. "Still some spots of rain, but the bulk of that precipitation moving through today and into tomorrow."

The coasts and valleys could see anywhere from 1.5 to 3 inches of rain from the storm, while the mountains could see 3 to 6 inches. An atmospheric river is a long narrow stream of tropical moisture in the atmosphere that can result in heavy rain or snowfall.

The Bond Fire burn scar in Orange County, along with the El Dorado and Apple Fire burn scars in San Bernardino County, are facing voluntary evacuation warnings. The vegetation on the hillsides has not had enough time to grow in order to hold the land in place during a storm.

Last week's storm brought heavy rain and mudslides to the Bond Fire burn area, damaging at least five homes, damaging several cars and uprooting trees. Some residents ignored mandatory evacuation orders and had to be rescued by firefighters.

A voluntary evacuation warning took effect Thursday morning in the Silverado, Williams and Modjeska canyons in the Bond Fire burn area. Residents were being advised to leave the area or prepare to evacuate quickly, particularly those with disabilities or mobility issues. Some streets in the area are restricted to local traffic.

Residents along Silverado Canyon Road were out fortifying fences and putting up additional sandbags.

The National Weather Service has issued a flood watch that will be in effect from Thursday evening until Friday morning for Orange County coastal and inland areas, Riverside County mountains, San Bernardino County mountains, San Bernardino and Riverside County valleys and the Inland Empire.

Orange County CEO Frank Kim said officials anticipated activating the county's emergency operations center.

silverado canyon storm
A mudslide in the Silverado Canyon area of Orange County during a rain storm. Dec. 14, 2021. (CBSLA)

"We're expecting at least a half-inch of rain" but with the ground already saturated with rain it has officials concerned.

"Even a quarter-inch on saturated ground can lead to a mudslide," Kim said.

The forecast also calls for the usual cautions for travelers.

"Moderate rain could create slick roads and travel delays along with high mountain snow accumulations and gusty winds," forecasters said. "Additional rain and lowering snow levels could impact travel this holiday weekend."

Daytime temperatures should be in the upper 50s to mid-60s Thursday, the mid-50s to lower 60s Friday and the mid-50s to around 60 on Christmas Day.

The Angeles National Forest tweeted Wednesday that due to the upcoming rain and low snow levels, several roads were closed.

Snow levels will initially be around 9,000 feet, but will fall below 8,000 by Friday afternoon, bringing some light snow to about 5,000 feet by Friday night into Saturday morning. A winter weather advisory is in place from midnight Thursday to 12 p.m. Friday for areas above 7,500 feet in San Bernardino and Riverside counties.

(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)

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