Hurricane Hilary prompts first-ever tropical storm warning for Southern California; "dangerous" flooding expected

Hurricane Hilary, which is expected to bring "rare and dangerous flooding" to the southwestern U.S., has prompted the National Hurricane Center to issue a tropical storm warning for Southern California for the first time in the region's history. 

The tropical storm warning, which was upgraded Friday night from what was also the first-ever tropical storm watch for the region, is in effect for most of Southern California, including large swaths of San Diego, Orange and Los Angeles counties, along with California's Catalina Island, according to the National Weather Service.

Hilary is now a major Category 4 hurricane. It is expected to decline in strength but bring heavy rainfall to parts of California after hitting Mexico. The storm's remnants are also likely to bring strong winds to some parts of California, including the Los Angeles Basin, the Weather Channel reports. 

"It is rare — indeed nearly unprecedented in the modern record — to have a tropical system like this move through Southern California," said Greg Postel, a hurricane and storm specialist at the Weather Channel who has a doctorate in atmospheric sciences.

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Hurricane Hilary was located about 285 miles southwest of the southern tip of the Mexican state of Baja California by Friday night, with maximum sustained winds of 130 mph, according to the National Hurricane Center. It was moving north northwest at 13 mph, the center said. 

In its advisory, the NHC warned of "life-threatening and potentially catastrophic flooding likely over much of Baja California and the Southwestern U.S. this weekend and early next week."  

The NCH has forecast that Hilary is expected to get close to the Baja California Peninsula's west coast this weekend, and will reach Southern California by Sunday night, when it is expected to weaken to a tropical storm.  

A tropical storm is defined as having winds of at least 39 mph, according to the National Weather Service. 

Forecasters said the storm is expected to produce 3 to 6 inches of rainfall, with maximum amounts of 10 inches, across portions of Mexico's Baja California Peninsula through Sunday night, with the possibility of flash flooding. The same rainfall amounts are expected across portions of southern California and southern Nevada.

Postel said there will likely be "damaging wind gusts," especially at higher elevations, in the area, and swells along the coast. 

Hurricane watches and warnings are in effect for parts of Baja California. Tropical storm watches and warnings are in effect for parts of the peninsula as well in addition to parts of mainland Mexico.

"On the forecast track, the center of Hilary will move close to the west coast of the Baja California peninsula over the weekend and reach southern California by Sunday night," the hurricane center said.

"Hilary is expected to weaken to a tropical storm by Sunday afternoon before it reaches southern California," it said.

California was drenched by a historic amount of rain this winter after being hit with an unprecedented number of atmospheric rivers. Chris Heiser, emergency services director for the city of San Diego, told CBS News Friday that those storms may have helped prepare officials for what is to come from Hilary.

"That really allowed us to get a feel for what the impact of heavy rains and winds are," Heiser said. "But this one's got some unique features. The amount of rainfall is substantial, especially up in the mountains. And the majority of the population of San Diego is at the base of those mountains."

"We're looking at this to be a significant storm, possibly one of those that sets records, and so we're preparing accordingly," he added.

Capistrano Beach in the Orange County city of Dana Point Friday was one of several where crews were building berms to protect the coastal community from high surf.

"We're getting ready now ahead of this event as it makes landfall to make sure we're prepared," said Chris Dargan, a spokesperson for California Governor's Office of Emergency Services.

Nevada Gov. Joe Lombardo announced late Friday that 100 National Guard troops had been activated ahead of Hilary.

Los Angeles County Sheriff Robert Luna said in a news briefing that "swift water rescue personnel and rescue aircraft are on alert and ready for immediate response."

The San Diego Padres, Los Angeles Dodgers and Los Angeles Angels all had home games scheduled for Sunday. However, those games have been shifted to Saturday double-headers in anticipation of the storm, Major League Baseball announced Friday.

The U.S. Navy on Friday night announced it would be moving vessels out of San Diego Bay to avoid damage from the storm. 

The Navy says ships and submarines will get underway Saturday from Naval Base San Diego, Naval Base Coronado and Naval Base Point Loma. The ships will remain at sea until Hilary passes over the region, the U.S. Navy said in a news release.

"In order to ensure the safety of our Sailors and ships, we are taking all necessary measures to mitigate potential damage to infrastructure and Third Fleet vessels caused by the storm," said Vice Adm. Michael Boyle, commander, U.S. Third Fleet, in the news release. "Safety remains our top priority, and putting all capable ships to sea makes it easier for us to manage the situation ashore."

Meanwhile, the National Park Service announced closures due to Hilary on their website. 

"Joshua Tree National Park managers are closing park areas that are vulnerable to extreme flooding. These closures will take place Friday evening, August 18, 2023. This is a preemptive measure in anticipation of Tropical Storm Hilary."

And in Los Angeles County, officials asked the homeless to stay away from waterways and river channels during the storm.

Ahead of Tropical Storm Hilary, LAHSA and County departments have activated additional outreach teams to work through the weekend to move unhoused residents out of high-risk areas. Stay away from #LACounty waterways and river channels before and after the upcoming storm. pic.twitter.com/03HNuOaMWi

— Los Angeles County (@CountyofLA) August 18, 2023

In:
• Weather Forecast
• Mexico
• Hurricane Hilary
• Hurricane

Kerry Breen

Kerry Breen is a news editor and reporter for CBS News. Her reporting focuses on current events, breaking news and substance use.

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