Tropical storm Hilary might cause 'life-threatening flooding' in some areas, says US National Hurricane Center

Tropical Storm Hilary was barreling along the Baja California peninsula in Mexico on Sunday and bearing down on the southwestern United States, where it was expected to cause heavy rain, dangerous flooding and possibly tornadoes.

The storm was downgraded from a hurricane shortly before 8 am Pacific time, weakening as it moved north, but the National Weather Service’s National Hurricane Center warned that it was likely to cause “catastrophic and life-threatening flooding” in regions unaccustomed to heavy rains.

Strong winds and waves buffeted a large swath of the Baja California peninsula on Sunday morning as the center of the storm moved up off the Mexican coast, and officials there expected it to make landfall later in the morning.

Mexican authorities said one person had died after a family’s vehicle was swept away in Mulegé, Baja California Sur, on Saturday night. Rescuers were able to save four of the five passengers, according to a local mayor, who said Sunday that the town of Santa Rosalía had suffered “very severe” damage.

In California, a light rain was falling in Los Angeles just after daybreak and forecasters warned that winds would intensify. Officials urged residents of some communities to evacuate, with several inches of rain expected there and in Southern Nevada.

Gov. Gavin Newsom of California declared a state of emergency in 11 counties, including Los Angeles, San Diego and Orange. Across the state, officials canceled events, closed parks and beaches, and deployed more than 7,500 emergency responders.

Here’s what else to know:

— According to the Hurricane Center, the tropical storm warning was the first ever issued for Southern California. The warning extended from the Mexico-California border to Point Mugu, about 40 miles west of Santa Monica by road. It also includes Catalina Island, where officials urged some residents to evacuate.

— The San Bernardino Sheriff’s Office on Saturday night ordered residents of several communities, including Oak Glen, Forest Falls and Mountain Home Village, to leave. Officials in Orange County urged people in Silverado Canyon and Williams Canyon to evacuate, and said the warning could become mandatory quickly if conditions changed.

— The weather service said that parts of California, including the Mojave Desert and the Imperial Valley, could see a tornado or two on Sunday. Tornadoes are not common in the Golden State. But it sees about 11 per year, the service has said.

— Mexico deployed more than 6,500 soldiers on Friday to the states of Baja California and Baja California Sur to help erect shelters, organize food banks and prepare for possible emergency rescues in areas popular with tourists.