Southern California braces for potentially dangerous debris flows from upcoming cold rainstorm

A storm bringing heavy rain and the potential for widespread flooding is expected to make its way into the Southern California region by Thursday, weather officials say.

The National Weather Service said the storm should arrive by Thursday night in most areas and will remain through Saturday, with the possibility of lingering showers into Sunday.

Weather officials are taking precautions with the heavy rainfall expected, warning residents about the potential dangers, including thunderstorms, flooded roads, debris flows in burn scar areas and gusty winds.

The atmospheric river is moving south from the Gulf of Alaska and CBS LA meteorologists call it the coldest storm since the beginning of the year.

CBS LA has issued a Next Weather Alert that will go into effect at 4 p.m. on Thursday and remain until Saturday for most of Southern California. The CBS LA news team is committed to keeping communities up to date about weather that could significantly impact their daily routines or commutes to work and school.

The NWS predicts metropolitan areas across Los Angeles and Ventura counties could receive between 1 to 2 inches of rain and areas in the mountains and foothills could receive between 2 and 4 inches of rain. They also predict a 10 to 20% chance of thunderstorms on Friday for all counties.

"As for rain rates, sticking with the previous forecast of widespread rain rates between a quarter and half inch per hour and locally as much as 0.75/hr," the NWS said.

The NWS said flood watches could be issued if precipitation rates remain consistent. All residents, especially those who live in burn scar areas, are urged to monitor emergency alerts. 

Evacuation and traffic advisories

Officials issued evacuation warnings for the Eaton, Palisades, Hurst, Kenneth and Sunset fire zones. Use the map below to see if your address falls within one of the zones. 

Caltrans said it will close SR-27 from Pacific Coast Highway to Grand View Drive in Topanga Canyon at 10 p.m. on Thursday.