Los Angeles, Feb 20 : New rounds of heavy rain soaked large portions of Southern California, and up to 37 million people are under flood alerts.

A low-pressure system in the Pacific is directing moisture onshore in California, resulting in widespread heavy rain and mountain snow, according to the US National Weather Service (NWS) as quoted by Xinhua news agency report.

Flash flood warnings were issued Monday morning for Southern California counties, including Santa Barbara and Ventura, where 2 to 5 inches of rain had already fallen, according to NWS.

Several roads across the state were closed because of flooding and rockslides, California's transportation agency reported.

Severe thunderstorms packing damaging wind gusts, hail and even a couple of brief tornadoes may develop Monday afternoon and evening, according to NWS.

Areas of rainfall and isolated thunderstorms continue to migrate northward across portions of northern and central California.

/IANS