Tropical Storm Hilary became a hurricane early Thursday morning as forecasters warned it could intensify and bring rare impacts into Southern California and the Southwest region.
"Hilary has the potential to bring significant impacts to the Baja California Peninsula and portions of the southwestern United States this weekend and early next week, including after it becomes post-tropical," the National Hurricane Center (NHC) said in an advisory.
Hurricane Hilary is forecast to intensify this week into a Category 4 hurricane with 130 mph winds. The storm is expected to weaken significantly before it reaches Southern California.
"Rapid strengthening is forecast, and Hilary could become a major hurricane by tonight or early Friday," the Miami-based center wrote in its latest advisory.
As of Thursday morning, Hurricane Hilary was a Category 1 storm with 75 mph winds and was located about 300 miles to the southwest of Manzanillo, Mexico, and also about 560 miles to the south-southeast of Cabo San Lucas, Mexico. The storm is moving to the west-northwest at 13 mph, according to the NHC.
A forecast model shows that the storm may still be a tropical storm when it impacts Southern California early Monday morning. The storm is then forecast to turn into a tropical depression between 12 a.m. Monday and 12 a.m. Tuesday.
Portions of the Inland Empire metropolitan area could see as much as 6 inches of rain. Much of Southern California, including San Diego and Los Angeles, could get 1 to 4 inches. Parts of the Sierra Nevada mountains and areas near Las Vegas, Nevada, could also receive as much as 6 inches of rain, according to the National Weather Service.
"Hilary has the potential to bring significant impacts to the Baja California Peninsula and portions of the southwestern United States this weekend and early next week, including after it becomes post-tropical," the NHC said in a forecast discussion. "Although it is too soon to determine the location and magnitude of wind impacts, interests in these areas should monitor the progress of Hilary and updates to the forecast. A Tropical Storm Watch is now in effect for southern portions of Baja California Sur, and additional watches or warnings will likely be required later today."
It also noted that heavy rainfall could result in flash flooding and landslides on the Baja California peninsula from Friday to Sunday. "Rainfall impacts from Hilary within the Southwestern United States are expected to peak on Sunday and Monday," it added.
Daniel Swain, a scientist at the University of California at Los Angeles, told CNN on Wednesday “multiple years’ worth of precipitation” could fall in Southern California.
“This does have the potential to be a very high impact event for portions of Southern California,” the National Weather Service's San Diego office also said. “There is still a degree of uncertainty in the forecast and more details will come on exact timing, location, and magnitude of impacts in the coming days.”
Despite the lull in the Atlantic hurricane season, the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center raised its 2023 prediction for the 2023 season from near-normal to "above-normal."
“Considering those factors, the updated outlook calls for more activity, so we urge everyone to prepare now for the continuing season," Matthew Rosencrans, lead hurricane season forecaster with NOAA center, said in a release on Aug. 10.
According to the NHC's hurricane map, there are currently no tropical storms, depressions, or hurricanes in the Atlantic basin. There are two disturbances with a 4o to 60 percent chance of forming a tropical cyclone within the coming two days, however.
"NOAA’s update to the 2023 outlook---which covers the entire six-month hurricane season that ends on Nov. 30---calls for 14-21 named storms (winds of 39 mph or greater), of which 6-11 could become hurricanes (winds of 74 mph or greater)," the release said. "Of those, 2-5 could become major hurricanes (winds of 111 mph or greater). NOAA provides these ranges with a 70 percent confidence. These updated ranges include storms that have already formed this season."
So far, there have been five tropical storms and Hurricane Don, which dissipated in the north Atlantic Ocean
“Considering those factors, the updated outlook calls for more activity, so we urge everyone to prepare now for the continuing season," Matthew Rosencrans, lead hurricane season forecaster with NOAA’s Climate Prediction Center, said in the release.