Tropical Storm kills at least one in Mexico and drenches Southern California

A rare tropical storm left at least one person dead as it blasted through Mexico’s Baja California peninsula on Sunday and crossed into heavily populated Southern California, threatening what meteorologists warned would be catastrophic flooding in desert communities not accustomed to sudden, drenching rains.

By early Sunday afternoon, Tropical Storm Hilary, the first tropical storm to hit California in more than eight decades, had already dumped three to four inches of rainfall in San Diego and surrounding areas, setting off small landslides and flooding roads.

In a measure of the storm’s feared effects, the U.S. Navy ordered ships and submarines to leave naval bases in San Diego, Coronado and Point Loma.

Meteorologists said the main threat from Hilary was the prodigious rainfall. Some locations in Nevada and the arid portions of California were forecast to receive one or two years’ worth of rain in one day, according to calculations by the National Weather Service. In Death Valley, normally one of the driest places in North America, flooding closed the main highway on Sunday.

California is inured to disaster, including the firestorms and mudslides that have been especially devastating in recent years. But tropical storms do not often figure on the list. Meteorologists have said the last tropical storm to make landfall in Southern California was at the outset of World War II, in September 1939. That storm, which tore through Los Angeles County, destroyed coastal homes, sank boats and flooded mountain resorts, killing nearly 100 people.

The rain brought by Hilary was a sharp departure from weather patterns in California, where most precipitation falls in winter and where summers often bring extreme desiccation.

On Sunday, the state was simultaneously threatened by fire and rain — and a small earthquake. Even as emergency officials focused on Southern California, a wildfire that has burned through more than 8,000 acres spurred evacuation orders near the Oregon border. And a 5.1 magnitude quake centered seven kilometers outside Ojai, a small city northwest of Los Angeles, shook parts of Southern California at 2:41 p.m. local time.

But the state’s main threat was from the storm. Meteorologists feared some of the most arid areas were extremely susceptible to dangerous flash flooding because the ground was hardened and unable to absorb the vast amounts of moisture that the storm was bringing.

“I’ve experienced zero tropical storms,” said Lori Gamble, a Palm Springs resident as the storm approached. “We don’t even know what a tropical storm is.”

Firefighters in Southern California accustomed to battling wildfires at this time of year were helping distribute sandbags. The Weather Service even warned of possible tornadoes in some inland areas. Tornadoes are rare in California, where only about 11 occur each year, according to Weather Service data.

In Mexico, one Indigenous community was essentially cut off by the storm, and flooding and mudslides closed a section of highway between the towns of Santa Rosalía and Mulegé in Baja California Sur state.

One person died after a family’s vehicle was swept away on Saturday night, and Santa Rosalía suffered “very severe” damage, its mayor said on Sunday.

More than a third of flights in and out of San Diego International Airport — and 40 percent of flights leaving Palm Springs International — were canceled.

Gov. Gavin Newsom, who traveled through Riverside and San Bernardino Counties on Sunday afternoon, declared a state of emergency in 11 California counties, including Los Angeles, San Diego and Orange. Some beaches, along with 10 state parks, were ordered closed. The governor said 7,500 emergency responders had been mobilized throughout the state.

In total, more than five million people in Southern California and southwestern Nevada were at high risk of excessive rainfall, with widespread flash floods expected through the early hours of Monday, according to the Weather Service’s Weather Prediction Center.

“High risk days are a big deal” that are rarely issued but account for nearly 40 percent of flood-related fatalities and more than 80 percent of flood-related damage, according to the Weather Service.

In recent decades, other tropical storms have brought tropical storm-force winds to the Southwestern United States, but only two have made landfall in California. Along with the 1939 storm, the other recorded tropical storm to make landfall in the state occurred on Oct. 2, 1858, when a hurricane shook San Diego, damaging homes, uprooting trees and causing inland flooding. The Daily Alta California described it as “one of the most terrific and violent hurricanes ever noted.”

Christopher Landsea, a forecaster with the National Hurricane Center, noted that there were no reported injuries or fatalities in the 1858 storm.

“Back then, San Diego was just a tiny little town,” he said. “San Diego is so different now that if that same hurricane were to hit today, then the damage could be catastrophic.”

As Hilary brought flooding to the West Coast, meteorologists also had their focus on two Atlantic storms. Tropical Storm Emily, which formed on Sunday morning, was not expected to threaten land. But a second tropical storm, Franklin, formed in the Caribbean on Sunday afternoon with winds of 45 miles per hour. It could affect Haiti and the Dominican Republic as early as Monday afternoon.

The Atlantic hurricane season runs from June to November, and forecasters are bracing for an especially unpredictable few months. An El Niño pattern, like the one expected to ramp up this season, typically impedes the formation of Atlantic hurricanes. But at the same time, extremely warm waters are unnerving experts and coastal residents, with heightened sea surface temperatures posing a range of threats, including the ability to supercharge storms.

That unusual confluence of factors led forecasters to raise their expectations for the number of named tropical cyclones this hurricane season to between 14 and 21 from between 12 and 17. But it also led them to acknowledge that the circumstances were puzzling and that solid predictions were even more difficult to make.

“Stuff just doesn’t feel right,” said Phil Klotzbach, a hurricane researcher at Colorado State University. “There’s just a lot of kind of screwy things that we haven’t seen before.”

Livia Albeck-Ripka, Anna Betts, Aline Corpus, Jill Cowan, Gaya Gupta, Judson Jones, Soumya Karlamangla, Corina Knoll, James C. McKinley Jr., Emiliano Rodríguez Mega contributed reporting.