Forecasters warn Southern Californians that a new storm could bring extremely dangerous flooding

The second atmospheric river to hit California in days could hit the central and southern regions late Saturday night and last several days.

This storm is expected to hit Southern California, including Santa Barbara and the greater Los Angeles area, on Sunday, with the worst flooding.

“Chances are increasing that a lengthy period of heavy rain will develop late Saturday night and continue through most of Sunday and Monday,” the Los Angeles National Weather Service warned.

The weather service predicts 3 to 6 inches of rain across Southern California from late Saturday to Wednesday. The region also saw torrential rain Thursday when the first strong atmospheric river dumped record rainfall in several areas and prompted water rescues.

This weekend's atmospheric river, a long, narrow moisture band that carries saturated air thousands of miles and discharges it like a fire hose, is expected to be stronger and stall over land.

The predicted deluge could cause urban, mud, rock, flash, and river flooding. In already saturated Southern California soil, another heavy rainstorm increases debris flow risk.

The National Weather Service warned Thursday that “with the ground already saturated from today's rain, onset of dangerous flash flooding will be much quicker with this next event and everyone, especially those near or in south facing mountains, needs to start preparing now for possible evacuations during or even before the storm hits".

The Weather Prediction Center predicts a Level 3 of 4 risk of excessive rainfall for coastal Central and Southern California, including Santa Barbara, on Sunday, and a Level 2 of 4 risk from north of San Francisco to Los Angeles.

Monday will bring a Level 3 of 4 threat of excessive rain to Santa Barbara and Los Angeles.