Updated

Several more inches of rain are forecast Monday for Southern California and Nevada as Hilary – which has now been downgraded to a post-tropical cyclone – continues to lash out at the American Southwest.

The National Weather Service warned in an advisory this morning that Hilary is "expected to produce additional rainfall amounts of 2 to 4 inches, with isolated storm total amounts to 12 inches, across portions of Southern California and Southern Nevada through today."

"Continued flash and urban flooding, locally catastrophic, is expected," the National Weather Service said, noting that the storm will continue to produce "strong and gusty winds in and near areas of elevated terrain today" and "life-threatening surf and rip current conditions."

At least 13 people have been rescued in knee-deep water in a homeless encampment along the San Diego River as a result of the storm, according to the Associated Press. Water rescues also have been confirmed by officials in Palm Springs and at the Canyon Mobile Home Park in Cathedral City.

SOUTHERN CALIFORNIA RESIDENTS FEEL MAGNITUDE 5.1 EARTHQUAKE AS TROPICAL STORM HILARY DESCENDS ON REGION

Hilary flooding in California

Cars are seen submerged in floodwaters on the Golden State Freeway as tropical storm Hilary moves through the area on Sunday in Sun Valley, California. (Justin Sullivan/Getty Images)

FOX Weather is reporting that Hilary will move to Idaho by this afternoon.

The National Weather Service says 1 to 3 inches of rain is expected in Idaho and neighboring Oregon, with some areas seeing up to 5 inches.

Earlier Monday, the National Weather Service's San Diego office said Sunday, Aug. 20 was the wettest day on record in the area, with 1.82 inches of measured rainfall. Prior to that, the previous record was 1.8 inches on Aug. 17, 1977.

California Gov. Gavin Newsom met with impacted communities across the southern part of the state Sunday night as Hilary, then a Tropical Storm, made landfall.

The storm was preceded by a magnitude 5.1 earthquake at approximately 2:41 p.m. PT on Sunday.

Tropical Storm Hilary damage in Los Angeles

A toppled tree from the tropical storm covers a car in Los Angeles on Monday, Aug. 21, after Tropical Storm Hilary passed through the area. (AP/Stefanie Dazio)

Newsom has expanded the number of counties under a state of emergency to ensure that more communities can access the support, services and resources needed in response to the storm, the governor's office said in a statement. He also issued additional emergency orders to give care facilities more flexibility to care for patients during the storm.

The governor spoke with local leaders, first responders leading recovery efforts and President Biden to address the ongoing impact of Hilary and the earthquake that struck Sunday afternoon.

The State Operations Center at the Governor’s Office of Emergency Services is activated 24/7, at the direction of the governor, and the state is closely monitoring the impacts of rain, wind, flash flooding and potential power outages. Officials are coordinating with state agencies to offer resources in preparation for other potential impacts of the storm, including tornadoes, earthquakes and earthquake aftershocks. 

Damaged road from Hilary in California

A view of gushing flood water and a damaged road during as Hilary passed through Oak Glen, California, on Sunday. (Roger Seheult/via REUTERS)

California has also activated its Medical and Health Coordination Center to monitor and arrange response efforts, and has issued an alert to all health facilities in the state.

The allocation of emergency resources across southern California and the Central Valley will continue amid the ongoing impacts of Hilary, Newsom's office said.

Hilary damage in California

Maura Taura surveys the damaged cause by a downed three outside her home after Tropical Storm Hilary went through on Monday in Sun Valley, California.  (AP/Marcio Jose Sanchez)

These resources include having medical assistance teams and medical assets on standby, the Flood Operations Center coordinating the distribution of more than 300,000 sandbags for flood-fighting efforts, the California National Guard prepositioning more than 350 soldiers and two dozen high water vehicles, and firefighters and rescue teams being deployed across impacted areas.

Hilary storm hits Palm Desert, California

Vehicles cross over a flood control basin that has almost reached the street on Sunday in Palm Desert, California. (AP/Mark J. Terrill)

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California is coordinating with Target, Wal-Mart, Lowe’s, CVS Health and other retailers and grocery stores to make sure essential supplies are available and emergency contingency plans are activated. The state is also coordinating with fuel suppliers, utility providers and telecommunications companies to maintain essential services.