The National Oceanic and Atmospheric Administration (NOAA) says Southern California could experience another wet winter, courtesy of El Niño — when ocean temperatures become unusually warm, leading to increased rain in the Southern U.S.
The science behind these predictions is more difficult than people think, says John Dumas, a science and operations officer for the National Weather Service.
“One of the things that a lot of people don’t realize is … El Niño is really an oceanographic phenomenon. Where it starts is out in the ocean. And then the effects of that get coupled into the atmosphere. And then finally, that can find its way into actual weather impacts here in Southern California,” he explains.
In a city like Los Angeles, where downtown only averages about 14 inches a year, he says, “All it takes is one or two extra [inches], and it’s a big weather year. … Or one or two less, and that’s when we start talking drought years.”
Even in a season when SoCal experiences less than typical rain, Dumas says, “If the one storm that comes through is an intense system, that can lead to the things like the debris flows where there were fire scars, or urban flooding. There can be a lot of impact just from one storm.” Under this advisory, residents should take El Niño as a general winter weather preparation signal.
“You can't ignore the signal,” Dumas says. “Whether you're positive it's going to happen or not, the signal is an El Nino year. [That] means in general, above average [rainfall], so you do all that normal winter preparation stuff. Because even without an El Niño, even if we only get that one storm this year that comes through, if it has just the right conditions with it, that could be a really impactful thing.”