Hilary updates: Over 1 foot of rain hits San Bernardino as LA avoids catastrophe

FEMA Administrator Deanne Criswell told reporters she is providing "continuous updates" to the White House about preparations ahead of the storm.

Criswell said she has also been in contact with California Gov. Gavin Newsom and Nevada Gov. Joe Lombardo to discuss "what type of support that they may need from FEMA and the federal family, but also to remind them that we are ready to support them as needed for this storm."

Criswell said they will not be moving any resources from Maui to California or Nevada to respond to the storm.

"We are still fully engaged in our efforts to help the state and people of Hawaii recover but it's also equally important that we are making sure communities that are in the path of Hilary also have the resources that they may need, and to what is likely going to be heavy impacts from rain and flooding," she said.

-ABC News' Justin Gomez

The San Bernardino County Sheriff's office has issued an evacuation warning to residents in parts of the county.

"An evacuation warning is not an evacuation order -- it's a warning to people to be on notice they could be asked to evacuate at any moment," San Bernardino County spokesperson David Wert told ABC News. "The purpose is to warn the population that there is an impending danger. They should start making arrangements to evacuate."

The storm is expected to hit San Bernardino County "pretty hard," Wert said, noting there is a threat of debris flowing into areas downstream of recent brushfires.

"Hopefully the order won't come, but we want people to be ready," Wert added.

-ABC News' Samira Said

The National Oceanic and Atmospheric Administration's Weather Prediction Center issued a rare "high risk" forecast for excessive rainfall for Sunday across a large swath of Southern California, from Palm Springs up toward Death Valley.

"High risk" forecasts are only issued a couple times a year on average, and 39% of all flood-related fatalities and 83% of all flood-related damages in the U.S. occur on those days.

A "moderate risk" for extreme rainfall has also been issued from Las Vegas to San Diego and Los Angeles. Numerous flash floods could unfold in these areas as well, with some of them potentially significant and very dangerous.

The deadliest hazard associated with tropical cyclones over the past decade is flooding from heavy rain.

-ABC News' Dan Peck

Winds from Hilary will reach tropical storm strength in Southern California on Sunday afternoon as the storm passes by.

Heavy rainfall is expected across the southwestern U.S., peaking late tonight through Sunday night. Rainfall amounts of 3 to 6 inches, with isolated amounts of 10 inches, are expected across portions of Southern California and southern Nevada. Dangerous to catastrophic flooding is expected.

Elsewhere across portions of the western U.S., rainfall totals of 1 to 3 inches are expected, resulting in localized, some significant, flash flooding.

-ABC News' Kenton Gewecke