California Braces for First-Ever Tropical Storm Watch as Hilary Intensifies to Category 4 Hurricane

Overnight, Hurricane Hilary rapidly intensified off the Mexican Pacific coast, far eclipsing predictions for its maximum strength. Now, southern California has been given its first-ever Tropical Storm Watch by meteorological authorities.

According to the latest report by the National Hurricane Center (NHC), which is operated by the US National Oceanographic and Atmospheric Administration (NOAA), Hurricane Hilary has maximum sustained winds of 145 miles per hour. The center of its eye is located about 470 miles west of the Mexican port of Manzanillo and 357 miles south of the southernmost tip of Baja California Sur State. The small volcanic island of Isla Socorro, Mexico’s most remote possession, is just 64 miles north of the eye’s center and being lashed with powerful winds.

#Hilary continues to rapidly intensify and is now a Category 4 Major Hurricane, with maximum sustained winds of 140 mph..

Latest Public Advisory from @NHC_Pacific: https://t.co/xucjiWFD7q?

Latest Discussion from @NHC_Pacific: https://t.co/qsHu4hVMow?#CAwx pic.twitter.com/sEeOkpM57N

— NWS San Diego (@NWSSanDiego) August 18, 2023

A day earlier, Hilary had only just barely reached hurricane strength and meteorologists expected the storm to only strengthen to having sustained winds of just 110 miles per hour. Its impact on the Pacific coast was also still in question. Now, massive amounts of rain and storm surge are projected to reach far inland, including as much as 10 inches of rain in some areas.

Hurricanes can rapidly intensify when passing over extremely warm water, since the weather “engine” that sustains them is based on rising warm, moist air found over tropical waters. Climatologists have warned that global warming is making the seas warmer, which in turn is making hurricanes stronger, too. Several major storms have been observed experiencing “bombogenesis,” or rapid intensification over a 24-hour period, even when only a few miles off the coast in recent years.

The western coast of Baja California Sur is presently under hurricane warnings and tropical storm warnings, with most of Baja California State being placed under hurricane watch through Sunday. Tropical storm watches line the coast of the Gulf of California and extend northward along the Pacific coast into the United States, reaching as far as Los Angeles, for Monday.

Forecasters have predicted “significant and rare impacts” across the arid region, including widespread flooding and high winds. For the low deserts east of the Southern California mountains, it is the first flash flood warning issued in over a decade, according to local media.

“Right now, it’s looking like we’ll still have a tropical storm when it moves into Southern California, but it’s going to be weakening pretty quickly,” National Weather Service meteorologist Brandt Maxwell told California media.

“The most important thing will be the heavy rain, which will be widespread, and there’s a distinct risk of flash flooding,” Maxwell said.

A tropical storm impacting the North American Pacific coast this far north is exceedingly rare, with a storm not landing in California since 1939 and a hurricane not hitting Baja since 1997, when Hurricane Nora passed eastward over the peninsula and brought tropical storm conditions to the US state of Arizona.