Hurricane Kay is forecast to track north, parallel to the Baja California peninsula, through Friday. It will then turn westward away from the coast just shy of the US border with Mexico, but not before making the closest pass to Southern California for a hurricane since 1997’s Hurricane Nora.
Kay is expectedn to remain at hurricane strength until it’s around 250 miles from San Diego, something only four other storms have done since 1950, according to the National Weather Service, before weakening as it moves closer.
But the storm doesn’t need to be strong “for this to be a major concern for Southern California,” said Brandt Maxwell, a San Diego NWS meteorologist.
Forecasters warn the system could amplify the region’s extreme heat woes, rather than relieve them.
Winds could gust more than 60 miles per hour as the system interacts with the mountainous terrain of Southern California. And those winds will be coming from the east, which means they will have a warming effect on coastal cities. As air travels down mountains, it is compressed and its temperature rises.
“We are not calling it Santa Ana winds, but they will have characteristics of them as they pass through canyons and the sloped terrain,” Maxwell told CNN.
The warm, dry winds from the east will increase the region’s fire risk. Temperatures could reach 100 degrees in the coastal areas of San Diego and Orange Counties on Friday.
“This happened in 1984 as a Category 1 Hurricane Marie well southwest of San Diego County forced temperatures to reach 100 in San Diego,” Maxwell said.
Overnight lows could remain in the 80s overnight Thursday and into Friday morning, making sleeping uncomfortable, especially for those without air conditioning.
Then, the relentless heat will “end abruptly and unusually” late Friday, the Los Angeles NWS said, as the tropical system’s cloud cover and rainfall move into the region, drastically reducing temperatures but creating new hazards.
“Confidence is rapidly increasing for a significant rainfall event across Southern California, Arizona, and eventually central California and Nevada into Saturday,” forecasters at the Weather Prediction Center wrote Wednesday.
East-facing slopes near the Santa Rosa and San Jacinto mountain ranges could see the heaviest rainfall, with as much as 4 inches possible through Friday. The WPC has issued a rare level 3 out of 4 outlook for excessive rainfall across this region for Friday.
Even though rainfall is desperately needed across parched Southern California, this much rain over a short period of time can cause creeks and rivers to rise rapidly.
“It’s never a good thing to get too much rain all at once, a trait all too common among slow-moving tropical storms,” the WPC said. “Thus, the flash flood potential is summarily also rapidly increasing.”