Every year, several potent storms brew in the Pacific Ocean, but they appear to lose their intensity by the time they reach Southern California. Meteorologist Henry DiCarlo offers an explanation as to why these Pacific storms, including those that achieve hurricane status, weaken upon reaching the Southland.
These tropical systems typically form south of Baja California near the Equator, where the water is warmer. “Warm water is what fuels and builds storms into tropical systems,” DiCarlo explained.
As these systems continue to grow in the ocean, often tracking parallel to Mexico, their eyes become well-developed and sometimes escalate to hurricane levels.
However, once a storm encounters the cooler waters off Baja or makes landfall, usually before reaching California, it rapidly loses strength. DiCarlo used a boiling pot of water as an analogy: “Once you turn off the heat, the water may continue to boil for a little while, but eventually, it’s going to dissipate.” Similar to the warm, humid, rising air that fuels tropical systems, once the storm moves over land, it loses its energy source and dissipates.
Although these storms weaken significantly, they can still bring substantial rain and wind damage. The last major tropical storm to hit Southern California was near San Pedro in September 1939, which caused considerable destruction and resulted in the death of 48 people.