Prospects for a strong El Niño have diminished, according to Scripps Institution of Oceanography. The latest forecast signals a much weaker event, dampening the hopes for above-normal rainfall in bone-dry San Diego.
The downgraded projection stems from a missing ingredient in atmospheric conditions, said climate researcher David Pierce with Scripps Institution of Oceanography.
“The atmosphere has to respond to the warm water and that really didn’t happen this year,” Pierce said.
A robust El Niño requires trade winds to push the warm water, as well as big thunderstorms over Indonesia moving east, Pierce said.
“And the reason those thunderstorms are important, even to us here in San Diego so many miles away, is because those thunderstorms inject water vapor into the atmosphere and that water vapor can be carried by winds to the West Coast where it falls as rain,” Pierce said.
El Niño is a warming of ocean temperatures in the tropical Pacific that occurs about every four to 12 years. It can cause above-average rainfall in San Diego as well as potentially damaging waves along the coast. The event can last from 9 months to two years.
Previous major El Niños have brought significant rainfall to the region, such as in 1997-1998 when San Diego received 17 inches of rain. In 1993, El Niño was credited with dumping 18 inches at Lindbergh Field.
Pierce said there is a bit of good news in the latest forecast: the warmer-than-usual ocean water means there’s no chance of a La Niña, which typically brings dry conditions to San Diego.
“A La Niña, 80 percent of the time we get less precipitation than normal in the San Diego region,” Pierce explained. “So we’re not going to have that condition which is really good because you know we’re in this terrible drought.”
Pierce said San Diego could still have an average winter, but any storms moving across the Pacific would be unrelated to El Niño.
