A rainfall bonanza could be coming to California Ocean temperature is comparable to strongest El Niño But there is more than one warm-water blob in the ocean
Fresno Bee
California is dreaming again of a cigar-shaped superstar hanging out in the sun for thousands of miles along the equator. El Niño, the moody blob of warm ocean water, is spreading in the Pacific right now.
Last year when El Niño began hinting at an appearance, media mania descended quickly, raising the possibility of a gully-washing winter to break the intense drought. A dud of a winter followed.
This time, the headlines might be right, say seasoned climatologists, such as Kelly Redmond of the Desert Research Institute in Reno. This is beginning to look like the rain festival of 1997-98, when the most powerful El Niño on record helped double average precipitation here.
But Redmond and other scientists always say this phenomenon has many personalities. Nobody really knows which one will show up. Will it suddenly cool down and turn into a wimp, as it did last year?
Maybe not this time.
El Niño prediction has not advanced much in the last 15 years, Redmond says. It is possible for science to learn more and fine-tune prediction, he says, but there
haven’t been many big breakthroughs since the 1990s.
“That said, I’ll be surprised if we don’t see something besides drought this winter,” Redmond says. “It’s darned hard to predict, so you have to be careful not to overstate or understate.”
And that may be the toughest part of following a capricious superstar, scientists say. They are trying to balance the message while explaining the event to folks who often just don’t get it.
Some people think it actually happens in California, scientists say. It does not.
“Some people think it’s a storm system,” says warning coordination meteorologist Jerald Meadows of the National Weather Service in Hanford. “It’s not that.”
WIND, WATER, ANCHOVIES
When you think of El Niño, think coastal Peru in South America, not California. Peruvian fishermen first noticed El Niño changes in the 1800s when their world-class anchovy fishery would sometimes collapse.
The fish need the plankton brought up by rising cold water that mysteriously stops every several years. Since the problem usually happened around Christmas, they called it El Niño — the child, or the Christ child.
Scientists later linked it to the dying trade winds that blow east toward Asia. As the wind dies, the sun heats the ocean down to about 100 yards below the surface. The warm surface water spreads along the equator until it covers an area twice the size of the United States, climatologists say.
The amount of heat energy has been compared to the atomic bomb. In the huge wet season of 1997-98, El Niño had more energy than a million Hiroshima bombs, scientists say. That heat energy causes the high-speed wind known as the jet stream to dip south — a powerful force drawing moisture and storms with it.
“It’s like being on steroids,” said consulting meteorologist Jan Null in the Bay Area.
That kind of power affects weather in many parts of the globe. There is often flooding in arid parts of Peru and Ecuador. Australia and Indonesia often experience drought. And, as the jet stream blasts across the southern states, it can mute the impacts of the Atlantic Ocean hurricane season.
Southern California can be pounded with moist storms for months at a time. Moving north in California, the effect tends to taper off, scientists say.
But unless El Niño is very warm and strong, it is not reliable, meaning anything could happen. That may be why the cooler episode of El Niño last year had little effect in breaking the drought, scientists say. And many other things are going on in the chaos of Earth’s weather.
“El Niño is the biggest player we know in global weather,” Null says. “It’s the superstar. But you have to remember, it’s not the only player out there.”
One of those players is the Pacific Decadal Oscillation, a decade-long swing between warm and cool ocean temperatures.
This longer-term event is influencing California’s drought, helping to create a vast pool of warm water in the Gulf of Alaska, says Fresno meteorologist Steve Johnson.
In the process, a freakish dome of air has risen over the last few years, bouncing storms away from California through the drought. The dome has been nicknamed by forecasters “the ridiculously resilient ridge.”
“I think people should know the warm water is still in the Gulf of Alaska,” Johnson says. “What does that mean for the strong El Niño building at the equator?”
It could be a good thing, because this setup apparently happened during the huge 1997-98 wet season. The Pacific Decadal Oscillation was in a similar warm cycle.
Even more telling, the water temperature right now along the equator is comparable to the ocean temperatures in summer 1997, Johnson says. More meteorologists suspect a very strong event this fall.
Says Johnson: “I think it’s possible we’re in for a hell of a wet season.”
Climatologist Redmond adds that people need to be patient if the downpours don’t start on Nov.
1. The 1997-98 season was not memorable until early February. He says he remembers seeing signs asking where El Niño was in January.
“Then the steady rain started on Feb. 2,” he says. “And it just kept going week after week.”
By the end of February, the community of Earlimart in Tulare County was overwhelmed with floodwater from the nearby White River. The normally small river also spilled onto Highway 99, shutting down the traffic artery.
FACES OF EL NIÑO
Bay Area meteorologist Null knows the splintered personality of El Niño. Null has a big collection of easily understood El Niño analyses, including a breakdown of precipitation in the four types of events.
El Niños are classified as weak, moderate, strong or very strong, depending on how warm the ocean becomes.
There have only been two very strong El Niños dating back 65 years — the 1997-98 and 1982-83 events. Most places in California got more than 150% of average rain and snow. Many got 200%, or twice the normal amount.
But if the event is just one step down in strength
— a strong El Niño — it’s not as certain. Of the four strong events since 1950, two seasons wound up below average in many California locations, including the mountains east of Fresno and east of Sacramento.
“Unless you’re looking at a very strong event, you have to be careful about how you explain it,” Null says.
The next question is a no-brainer: Will California suffer catastrophic flooding during a very strong El Niño? Damage during the 1997-98 monster season ranked 10th among the costliest flood years, according to Null’s statistics.
The other very strong El Niño, 1982-83, is third. The worst year was 1994-95 during a moderate El Niño. The damage was $1.95 billion.
The rest of the 10 worst flooding years included two La Niña years when the water at the equator was cooler than average. It may seem odd, because La Niña often means less rainfall in California. The other four flood years happened when the ocean temperature was average.
“What does that mean? Flooding happens here,” Null says.
Why does El Niño have so many faces? Climatologist Redmond says the variations could have something to do with the locations of the warmest areas, but there could be many other factors as well.
“Does it make a difference if the patterns of warmth are nearer Peru and the Galapagos?” he asks. “We’re talking about a lens of shallow warm water across thousands of miles of the planet. We just don’t know enough about it yet.”
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