Hurricane Hilary is expected to weaken in strength but parts of the west coast and U.S. Southwest are still bracing for heavy flooding brought on by the now Category 3. Image courtesy NOAA

The storm’s maximum sustained wind speeds are topping out at 115 mph.

Flood watches are in effect from southern California through Arizona, extending north to Oregon and Idaho.

Forecasters now expect Hilary to weaken to a tropical storm before arriving in U.S. coastal waters sometime late Sunday. Southern California and parts of Arizona are expected to be the hardest hit areas.

The storm was downgraded from a Category 4 to a Category 3 Hurricane Friday.

The National Weather Service is forecasting severe thunderstorms in southwest Arizona, which will bring intense rainfall and could lead to flash flooding and tornadoes.

The Los Angeles County Sheriff’s Department is advising people to leave Catalina Island in Los Angeles ahead of the storm.

The U.S. Navy on Saturday started moving some of its ships out to sea to avoid being damaged in port at Naval Base San Diego. The nuclear-powered USS Nimitz aircraft carrier was the first to leave Saturday morning.

National Hurricane Center forecasters late Friday continued to warn of life-threatening and “potentially catastrophic” flooding possible in the U.S. Southwest early next week.

On Friday, the Los Angeles County Office of Emergency Management posted on X the area is facing a tropical storm watch and residents should “prepare now for high winds, excessive rainfall, high surf, flash floods” and the possibility of power outages.

NHC officials noted in an earlier advisory that the government of Mexico has upgraded the hurricane watch to a hurricane warning on the west coast of Baja California northward to Cabo San Quintin. It also has upgraded the tropical storm watch to a tropical storm warning north of Loreto on the east coast of Baja California and north of Guaymas in mainland Mexico.

And a tropical storm watch has been extended westward from the Orange/Los Angeles County Line to Point Mugu, forecasters said.

Forecasters say Hilary will drop up to 10 inches of rain in some areas as the storm approaches the Baja California peninsula over the weekend with tropical-storm-force winds.

Hilary was expected to produce 3-6 inches of rain throughout portions of the Baja California peninsula through Sunday night, with isolated maximum amounts of 10 inches and locally significant flash flooding possible.

Heavy rainfall of 2-4 inches is also expected to impact the southwestern United States from Friday through early next week. In isolated cases, it could be in excess of 8 inches across southern California and southern Nevada.

Large wave swells generated by Hilary are expected off the southwestern Mexican coast and Baja California over the next few days.

In May, the NHC said it expected a “near-normal” hurricane season,” and in June, the Climate Prediction Center said an El Nino weather phenomenon had developed.