New Delhi, Dec. 24 -- Parts of Southern California are under a High Risk (level 4/4) of excessive rainfall through Thursday morning, according to the National Weather Service (NWS) Weather Prediction Center.

The system, fueled by a broad plume of moisture from the Pacific, is expected to bring very heavy rain, creating severe, widespread flash flooding. The NWS warned that "areas that normally do not experience flash flooding will flood," and that "lives and property are in great danger."

AccuWeather meteorologists emphasized the severity of the storm. Senior Meteorologist Tyler Roys said, "The downtown Los Angeles area is projected to receive 4-8 inches of rain through this week alone, which is two to three times the entire December hi...