Editor's note:Read our coverage of Hurricane Hilary forSaturday here.
CNN—
Concerns are growing. Hurricane Hilary will bring heavy flooding to the US Southwest and parts of California as it moves infrequently across the region Sunday and early next week, prompting a tropical storm warning for parts of Southern California.
Hilary could throw more than thatannual amount of rainin parts of three states: California, Nevada and Arizona. Because of the threat, parts of California face a rare high risk of excessive rain. This level 4 out of 4 threat is the first ever issued for this part of Southern California.
Hilary was a powerful Category 4 hurricane that churned about 325 miles south of Cabo San Lucas, Mexico on Friday afternoon with sustained winds of 130 mph with gusts higher thanNational Hurricane CenterHe said.
The storm experienced incredibly rapid intensification from Thursday to Friday, strengthening from a tropical storm to a Category 4 hurricane in just 24 hours. Hilary is forecast to remain a Category 4 storm as it approaches Mexico's Baja California peninsula through Saturday.
Forecasters have issued hurricane and tropical storm warnings and watches for Baja California, including the Los Angeles area and extending as far north as Point Mugu in Ventura County and northwestern Mexico as Hilary's center approaches over the weekend.
It remains awide range of outcomesfor the strongest winds in the US as the storm moves north over the next few days. Small deviations in the hurricane's track could change the forecast for the heaviest rain and wind.
The hurricane is moving faster than expected, so Mexico and California are also expected to feel the impact earlier than early forecasts indicated. The center now predicts Hilary's core will be "very close to central Baja California Saturday night and move inland over southern California by Sunday night."
The NHC also noted that strong winds and heavy rains will hit areas far before they see the center of the hurricane.
Hilary is more likely to make landfall in Mexico and California, but if it makes landfall in California as a tropical storm, it will be the first such storm to make landfall in California in nearly 84 years, according to the National Oceanic and Atmospheric Administration.
The first tropical storm watch was issued Friday morning for parts of Southern California, the National Hurricane Center said, stretching from the California-Mexico border through Los Angeles County. The watch was changed to a warning in an update Friday night.
"The threat of significant wind gusts continues to increase for the northern parts of the Baja California peninsula and the southwestern United States, especially in areas of mountainous terrain," hurricane centerHe saidThursday night.
The Southwest is preparing for significant flooding
Hilary is expected to weaken significantly before reaching Southern California and parts of the Southwest, but regardless of strength, the storm will add to heavy rainfall and increase the risk of flooding.
Heavy rainfall is expected to begin affecting the southwest on Saturday and early next week, with the most intense showers likely on Sunday and Monday.
It is difficult to overestimate how high the risks of excessive rain are. High risks are issued on average less than 4% of days per year, but they are responsiblefor 83% of all flood-related damages and 39% of all flood-related deaths, the research of the Weather Forecast Center shows.
Southern parts of California and Nevada could get 3 to 5 inches of rain with isolated amounts of up to 10 inches. Rainfall of 1 to 3 inches is expected in the central parts of those states, as well as in western Arizona and southwestern Utah.
Thanks to Hilary, "multi-year precipitation could potentially drop in some of the driest parts of California," Daniel Swain, a climatologist at the University of California, Los Angeles, said Wednesday.
Among these places is Death Valley in California, the hottest place on Earth. Death Valley typically receives about 2 inches of rain throughout the year, according to the NWS. Moisture from Hilary could release enough rain to give Death Valley a 1-2 years amount of precipitation in one day. And Las Vegas could get 2 to 4 inches of rain. It averages only 3.75 inches of rain per year.
Prolonged rain can soak the ground and overflow waterways, potentially exacerbating the risk of flooding.
The Mojave National Preserve, which straddles the California-Nevada border, is closed until further notice due to possible flooding from the storm, spokeswoman Sierra Willoughby told CNN on Friday.
A weekend flood warning has been issued across Southern California, from San Diego to Los Angeles, as residents prepare for potential flooding.
National Weather Service in Los Angelesalso warnedpotential for dangerously high waves, rip currents and coastal flooding. Various county departments have spent the past few days preparing for the storm and have rescue personnel ready to respond immediately, Los Angeles County Sheriff Robert Luna said during a news conference Friday.
Luna said the main concern is protecting members of the homeless community. The greater Los Angeles area is home to about 75,000 homeless people, with more than 46,000 within the city limits, according to a 2023 estimate.Los Angeles Homeless Authority. California is generally homehalf of all Americans without shelter, according to federal data.
The county is reaching out to people, especially those staying in parks or near waterways, to provide them with temporary housing, Luna said. The sheriff's department is mapping out campsites and making aerial announcements of the coming storm with relief teams on the ground, he said.
"We hope the storm causes no damage and more importantly no loss of life," the sheriff said. "But we're going to prepare for the worst possible scenario, not only to help people here in our county, but if we're not affected or affected, we'll be a resource to other neighboring counties as needed."
Tropical activity on the rise in the Atlantic
The National Hurricane Center is monitoring areas for possible tropical development.
Not to be outdone by the eastern Pacific, the Atlantic is bracing for a dramatic increase in tropical activity in the coming days. Four separate problem areas span the entire basin from west of Cabo Verde Island to the Gulf of Mexico.
Of greatest importance to the United States is the area inextremely warm Gulf of Mexicowhere atmospheric conditions may converge and support tropical development next week. An area of low pressure could slowly organize in the basin, strengthen and take on tropical characteristics over the western gulf by midweek.
Three separate areas of concern are in the tropical Atlantic. An area of disorganized showers and thunderstorms west of the Cabo Verde Islands could organize into a tropical depression over the weekend and could further strengthen into a tropical storm. Another area of disturbed weather to the west could become a tropical depression by early next week. Another area has little chance of acquiring tropical characteristics near the Lesser Antilles.
CNN's Eric Zerkel, Taylor Ward and Monica Garrett contributed to this report.