Though not a certainty, the “smart” money is on the building El Niño in the Pacific Ocean leading to a wetter-than-normal winter this year. It now seems more a question of how much — and how long — the precipitation will last, not whether it will happen.
“It’s like it (El Niño) is almost too big to fail,” said San Diego Lifeguard Lt. John Sandmeyer following a recent briefing he and other city officials had from the National Weather Service about the El Niño/La Niña cycle. “The atmosphere is loaded with moisture, and it will come, though it’s uncertain whether the ocean track will go over Central California, Southern California or Mexico,” said Sandmeyer. He described the building El Niño, explained by weather forecasters, as a “significant bank of water 2.23 degrees (much) warmer than usual and hundreds of feet deep out in the South Pacific.”
“El Niño,” “The Christ Child” in Spanish, referring to its impact during Christmas in South America, is the “warm” phase of the El Niño Southern Oscillation (ENSO). It is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific. El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. The “cool” phase of ENSO is called La Niña, translating as “The Girl.”
The ENSO cycle, both El Niño and La Niña, causes global changes of both temperatures and rainfall. Because El Niño’s warm pool feeds thunderstorms above, it creates increased rainfall across the east-central and eastern Pacific Ocean. This anomaly happens at irregular intervals of two to seven years lasting nine months to two years, with the average period lasting five years. On the West Coast of the United States, El Niños typically cause significantly wetter winters.
David Pierce, climate researcher at Scripps Institution of Oceanography, verified that an El Niño is in fact highly likely this winter. And, Pierce noted, this current El Niño could be enhanced by a concurrent ocean anomaly known as “The Blob.”
“The Blob is a patch of unusually warm water off the Gulf Coast of Alaska,” Pierce said, adding, “The Blob has moved down and has been hanging out over the West Coast, including California, for more than a year.
“It’s hard to tell how much effect El Niño and The Blob will have,” said Pierce, pointing out that “every indication is both will continue through this winter.”
Pierce offered a gambling analogy to describe the likely impact of an El Niño/The Blob on California’s winter climate.
“It’s like having dice that are loaded,” he said. “You don’t know what (precipitation) number is going to come up until you roll the dice. But the odds are we’re more likely to have a wet winter, though it’s not actually guaranteed.”
Pierce said other factors, like tides, can have a huge impact when coupled with El Niños in the amount of disruption such an event can cause.
“In the 1982-83 El Niño,” he said, “a lot of the storms happened during high tides, which caused a lot of coastal damage. There was less coastal damage during the 1997-98 El Niño because storms weren’t associated with high tides.”
Pierce described El Niños/La Niña as “a very natural phenomenon known from paleoclimatological records to have been going on for thousands of years.” He added El Niños/La Niñas have been happening intermittently for the past century with varying results.
“In 1997-98, California got 180 percent of normal precipitation,” Pierce said, pointing out that that’s extreme and noting El Niños typically average about 30 percent higher precipitation than usual. “You can’t really make a prediction for how much it will depart from normal,” he said.
Noting that El Niños “cause more moisture to go up into the atmosphere in the form of clouds and precipitation,” Sandmeyer pointed out this temperature-moisture oscillation serves as an “engine” driving weather.
“It’s the unequal warmth of the Earth’s surface that causes weather,” the lifeguard said, adding that El Niños create a “bigger engine” that translates into greater-than-normal rainfall.
Above-average rainfall is going to be more impactive throughout San Diego County, including along the coast. Nearly 54,600 San Diego County residents, about 1.75 percent of the total, live in 100-year flood zones, mostly known flood plains that could be subject to flooding during El Niño-fueled rainstorms over the next several months, according to a report released by the National University System Institute for Policy Research.
Sandmeyer, team leader for the San Diego River Rescue Team, which is charged with safeguarding people along waterways during heavy rains and flooding, said El Niño’s impact along the coast could be pronounced.
“It would create pollution and add to the erosion of the beach in some areas,” he said.
“like Dog Beach and Ocean Beach and along river mouths.” He added that first responders are gearing up for the possibility of an especially wet winter.
“The River Rescue Team responds to anybody trapped in or around moving water,” Sandmeyer said. “Preparations are being made throughout the city and county,” he added, “coordinating between lifeguards, fire and police departments and the city’s Traffic Division. We’re planning for flooding. So there’s a lot of discussion going on. It’s a big deal.”
Sandmeyer said it’s not the amount but the duration of rain that falls during an El Niño event that could prove to be the most problematic.
“The biggest threat we’ll see in San Diego is if we get three or four days of rain with significant downpours,” said Sandmeyer. “Then we’re going to see areas, including roads, flooded because they won’t have time to drain. We’re gearing up for evacuations and closures of blocked areas and (residential) complexes. It’s a wide swath of the county that’s under the hazard level when there are significant rainstorms.”