Posts Tagged El Nino

Oct 7 2015

Will El Niño ‘solve’ drought? Not if the rain falls in Southern California

Lake Shasta and Northern California’s other largest reservoirs, Oroville and Trinity, account for almost a quarter of the state’s surface water supplies. Combined, they can hold more than 10.5 million acre feet – or 3.4 trillion gallons – of rainwater and snowmelt. To put that in perspective, the city of Sacramento in 2014 used just 94,000 acre-feet. Greg Barnette Redding Record Searchlight file

In recent weeks, conditions have gelled for what forecasters say could be one of the strongest El Niño weather patterns in recorded history. Will it substantially ease California’s historic drought? If the storms center on Southern California, the answer is probably not.

Experts stress that El Niño is notoriously unpredictable, and when its storms do hit the state, they’re prone to soaking the southern third of California. While more than 75 percent of the demand for irrigation and drinking water is in the south state, the backbone of California’s water supply and delivery system – and most of its reservoir capacity – is in the north.

“We’re much better off if it rains in the north than in the south,” said Peter Gleick, president of the Pacific Institute, an environmental policy group based in Oakland.

In a typical year, about 75 percent of the state’s annual precipitation falls north of Sacramento, in the form of rain and mountain snow.

Four years into the drought, conditions have been far from typical. On April 1, when California snowpack generally has reached its greatest depths, the Sierra snowpack was at just 5 percent of normal. Researchers said it was the lowest it had been in more than 500 years. State officials say the 2015 “water year” that ended Sept. 30 recorded the warmest high-elevation temperatures in the 120 years people have been keeping track.

Those conditions have strained California’s massive water-delivery system, a series of reservoirs and canals operated by the state and federal governments. The infrastructure was built to take advantage of historic weather patterns, with a focus on regulating flows to prevent downstream flooding in heavy storms and capturing snowmelt to buoy the state through summer and fall.

“If you only get a series of early spring and early summer rainstorms, we’re not really designed to capture that runoff,” said Noah Garrison, a water-law expert and geologist at the UCLA Institute of the Environment and Sustainability.

The state has approximately 1,500 reservoirs, which portion out water over the year to meet demand for farm and landscape irrigation, drinking water, and fish and wildlife habitat. The vast man-made conveyance network is capable of funneling Mount Shasta snowmelt 700 miles south to San Diego.

The trick is storing the right amounts at the right times to ensure there is adequate water to meet yearlong demand in a state with enormous regions of developed land that get minimal precipitation or have just one wet season a year.

We’re much better off if it rains in the north than in the south.

Peter Gleick, Pacific Institute

In all, California has 43 million acre-feet of reservoir storage space, almost three-quarters of it north of Fresno. The largest of these reservoirs, Shasta, Oroville and Trinity in far Northern California, account for almost a quarter of the state’s surface water supplies.

Jay Lund is a civil and environmental engineering professor at UC Davis and heads the university’s Center for Watershed Sciences. During a recent interview, Lund held up a chart that showed a seemingly random scattering of points on a graph. The dots represented Sacramento River runoff during El Niño years, he said, underscoring the uncertainty of whether this year’s El Niño will substantially raise water levels in the northern reservoirs.

“It looks like a shotgun blast,” he said. “You wouldn’t want to bet on this. Maybe we will get a lot of water. Maybe we won’t.”

El Niño conditions occur when ocean temperatures warm along a stretch of the equatorial Pacific roughly twice the size of the United States. The warming leads to a shift in weather patterns that typically cause West Coast storm systems to move south.

During weak or moderate El Niño events, in which Pacific water temperatures rise by a modest amount, it’s hard to find a consistent rain pattern in Sacramento, according to a Sacramento Bee review of data back to 1950. The average precipitation in those years was 18 inches – about normal for the city. Stronger El Niño years – when ocean temperatures rise by a significant amount as they have this year – are more encouraging. During those years, rainfall in Sacramento averaged 24 inches, roughly 130 percent of normal.

If that happens, and El Niño douses central California as far north as Sacramento, it would substantially ease the burden on the state’s water supply – even if the storms don’t dump deep snow in the northern mountains, said Maury Roos, an hydrologist with the state Department of Water Resources.

Roos said there are a number of smaller reservoirs south of Sacramento that help supply the state’s Central Valley farm belt. Crop irrigation, most of it in the Valley, accounts for about 80 percent of the “developed” water in California, meaning water that people put to use.

Map of precipitation forecast and reservoir levels

“If it gets as far north as where we are, then it will help a lot more,” said Roos from his office in Sacramento. “Then you can help to refill some of the major reservoirs around the rim of the Valley.”

If the bulk of the heaviest rains stay further south, a wetter Southern California will help, but not nearly as much.

“We’re just not set up to handle the capacity, the total volume of water that we’re really dealing with,” said Garrison, the UCLA geologist. “A 1-inch rainstorm in L.A. can produce 10 billion gallons of runoff … most of which ultimately will end up flowing down the L.A. River and out to the ocean. We don’t have capacity to capture large events like that and really put them to use yet.”

Still, the situation has improved since the state’s last deep drought in the early 1990s. Several major Southern California cities and irrigation districts have made strides in recent years to capture more stormwater, reduce local use and make imported reserves last longer.

Rich Atwater, executive director of the Southern California Water Committee, said the region, on average, now gets about 12 percent of its water supply from locally captured stormwater. Southern California is investing in infrastructure improvements that should increase this capacity 5 percent, he said.

The region also gets about 10 percent of its water from recycled sewage, he said. He expects that figure to double in the next 25 years. That’s based, in part, on an ambitious plan for what would easily be the largest wastewater recycling effort in the state. The Metropolitan Water District of Southern California is discussing a project that would produce 168,000 acre-feet of potable water using treated sewage to replenish groundwater supplies.

The water district, which serves 19 million customers, recently spent close to $3 billion on a reservoir and tunnel project at Diamond Valley Lake near Hemet in Riverside County. The reservoir can capture 800,000 acre-feet – or about 260 billion gallons – of water. But for now, there’s no ready infrastructure for funneling in storm runoff from around the region. The reservoir will capture rain that falls directly in its walls, but it is only plumbed to receive water piped from Northern California.

A 1-inch rainstorm in L.A. can produce 10 billion gallons of runoff … most of which ultimately will end up flowing down the L.A. River and out to the ocean. We don’t have capacity to capture large events like that and really put them to use yet.

Noah Garrison, UCLA Institute of the Environment and Sustainability

The biggest benefit to Southern California from El Niño storms could be replenishment of groundwater supplies. In the drought, government surface deliveries have been slashed to a fraction of what they have been in average rainfall years. Central and Southern California cities and farms have been furiously pumping groundwater to make up for the loss.

Over the decades, several Southern California water districts have invested in groundwater banks and groundwater recharging projects to offset the unreliability of imports from the north and the Colorado River. These projects make use of imported water or natural flows that are channeled into swampy or porous areas where the water can seep into the ground for later pumping.

Kern County has created the state’s largest water bank, primarily to help irrigate its $7.5 billion agricultural industry. The storage network, spread across numerous irrigation districts, can hold 5.7 million acre-feet of water.

In the drought, even this massive system has been depleted. Jon Parker, general manager of the Kern Water Bank Authority, said his district alone can store up to 1.5 million acre-feet. In the drought, pumping has lowered that level to 500,000 acre-feet.

Robb Whitaker, general manager of the Water Replenishment District of Southern California, said drought-related pumping has similarly drained the groundwater stored under his district, which supplies about 40 percent of the water for 4 million people in southern Los Angeles County. He said a single wet El Niño year could put more than 150,000 acre-feet of water back into the ground.

“The basins are very, very dry. … They’re ready to capture water,” Whitaker said. “It’s like a dry sponge, and we’re hopeful we’d be able to get about twice the normal capture, if not more. In that case, we could be caught up in two or three wet seasons.”

The challenge with water banks and groundwater recharging is that too much rain too fast can overwhelm the system. Unlike a traditional reservoir, the basins that capture groundwater need time for that water to seep in.

“If the engineers and the water managers could control all the knobs like the great and powerful wizard of Oz, they would like it to come down at a moderate pace for a long time, so the system could sort of absorb it as it happens,” said Kelly Redmond, deputy director and regional climatologist for the federal government’s Western Regional Climate Center in Reno.

“If you overwhelm the system, some of it will go into groundwater recharge, but a lot of it will just go out to the ocean, and I guess your perspective on whether that’s wasted water or not might depend on if you’re a water manager or a fish.”

At the most basic level, a prolonged soaking would keep Southern California residential landscapes green longer without sprinklers. Some residents are hoping to extend that run with rain barrels, which while not widespread, have gained some traction through rebate programs.

Geri Cicero, a retired administrative assistant from Costa Mesa, is ahead of the curve on that front. She said that even before the drought, she installed rain barrels and other water-catching devices around her property. She’s anxious for an El Niño to fill them up for later landscape use.

“If you walked around my house, you’d see bucket after bucket and barrel after barrel,” she said. “It’s almost like a game for me. I really enjoy it.”

Atwater, with the Southern California Water Committee, has rain barrels, too. While they’re helpful in getting people to think about how much water they use on their landscape, he said, they can only do so much in solving the state’s water storage needs. He said he uses larger rain barrels than most people, and they’re empty within a week or two after a storm.

“A 50-gallon rain barrel doesn’t go very far,” he said.

Water storage

Shasta Lake was 35 percent full on Saturday. That’s 58 percent of the amount of water it would normally have this time of year. How the state’s largest reservoirs compare:

Reservoir Size (acre-feet) Pct. full Pct. of normal
Shasta Lake 4,552,000 35% 58%
Lake Oroville 3,537,577 30 49
Trinity Lake 2,447,650 22 32
New Melones Lake 2,400,000 11 20
San Luis Reservoir 2,041,000 19 40
Don Pedro Reservoir 2,030,000 31 47
Lake Berryessa 1,602,000 52 70
Lake Almanor 1,308,000 55 96
Lake McClure 1,024,600 8 19
Pine Flat 1,000,000 12 35
Folsom Lake 977,000 18 31

Source: California Department of Water Resources

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Oct 1 2015

Dolphins, Pelagic Red Crab, Sun Fish Point to El Nino Coming to Northern California

The subjects of science are often witnessed through microscopes, tiny squiggly things writhing in a petri dish. But last week as a large research boat drifted through the Gulf of Farallones National Marine Sanctuary, science was getting scrutinized through binoculars and even the naked eye.

For the 12th year in a row, researchers from Point Blue Conservation Science, the Gulf of Farallones and Cordell Bank Marine Sanctuaries were spending 10 days on the ocean outside the Golden Gate Bridge taking a scientific snapshot of ocean life.

“Our goal is to understand how ocean conditions affect food for birds and whales,” said Jaime Jahncke of Point Blue.

Over several days the team collected krill samples, tested for signs of ocean acidification and attempted to lay eyes on as many critters as possible.

“Our sampling effort looks at birds, mammals, krills, boat activity ,” said Jan Roletto, research coordinator for Gulf of Farallones National Marine Sanctuary.

A researcher scans the ocean for seabirds during a recent scientific cruise in the Gulf of Farallones National Marine Sanctuary.
Photo credit: Joe Rosato Jr.

But this year’s gathering turned-up some unusual phenomenon, which scientists believe are signs of an El Nino year – which draws unusually warm waters to Northern California. For the first time in decades, scientists saw schools of hundreds of common dolphins which aren’t common to the Bay Area, but rather the typically warm waters of Southern California.

“It’s a sign the water is more warm than we normally see,” Roletto said. “And that’s a sign of El Nino.”

Scientists have recorded large pockets of warm water along the West Coast over the last two years – which they’ve affectionally nicknamed “the blob.”

“This year has been particularly interesting,” Jahncke said. “The ocean has been really warm because of ‘the blob.’ ”

During an expedition earlier this summer, the scientists noted fewer krill in the ocean which in turn was driving humpback whales closer to shore near Half Moon Bay and Monterey to seek out fish.

“There are more whales visible from the mainland,” Roletto said. “That’s because that’s where the fish are being concentrated.”

A small fish sits among a sampling of krill collected by researchers during their scientific cruise.
Photo credit: Joe Rosato Jr.

In addition to dolphins, Roletto said the group spotted other typically warm water creatures venturing north. Sleepy-looking sun fish were seen basking in the waters. And the researchers’ nets pulled up a curious traveler — a small red pelagic crab that normally makes its home near Baja.

“The last time I personally saw in this region red pelagic crabs was in the 1983, 1984 El Nino,” Roletto said.

Roletto said the lack of krill and juvenile rockfish which are normally abundant along the coast was posing hardships on common murres which have been recently turning-up starving and dead on Northern California beaches. Roletto said the young birds count on juvenile rockfish to survive. She pointed out similar die-offs occurred in past El Nino years.

“That’s pretty extreme,” Roletto said, “pretty significant indicator that something is missing in the eco system.”

As part of the research, observers armed with binoculars lined the boat’s upper deck, calling out every bird and mammal along a set swath of ocean near the Farallon Islands. Sea lions, whales and even plain old seagulls became part of a moving record of the area’s life. The results are compared to previous years’ records to help paint a picture of the changing conditions.

A research team hauls in nets designed to collect krill and other small sea creatures in the Gulf of Farallones National Marine Sanctuary.
Photo credit: Joe Rosato Jr.

“It’s really interesting because things change from day to day,” said Danielle Lipski of Cordell Bank Marine Sanctuary. “Sometimes we’ll see lots of whales and seabirds and in other areas we won’t.”

Jahncke stared off across the churning waters as the boat bobbed and jibed across rolling swells — when something suddenly caught his eye. In the distance came the telltale blowhole spout of a whale.

“Do you see it?” he said enthusiastically, quickly tapping record of the sighting into his computer. Then he leaned back to appreciate the view, watching as the ocean swallowed the meandering giant.

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Sep 23 2015

‘The Blob’ Fueling Drastic Changes Under The Sea Ahead Of El Niño

It’s the crack of dawn on a recent morning at Fisherman’s Landing in Point Loma, and the docks are bustling.

Dozens of enthusiastic anglers have just returned with a boatload of bluefin tuna, dorado and yellowtail.

It’s been a banner season, said Andrew Dalo, who books reservations for Point Loma Sportfishing.

“I’ve got overnight and day-and-a-half boats that are catching 100- to almost 200-pound bluefin tuna up off our coast here, out west and up north,” Dalo said. “And that’s stuff that we don’t even normally see up here, let alone go after.”

A group of anglers on a Point Loma Sportfishing expedition pose with their bluefin tuna catches, weighing 100 to 200 pounds each, July 29, 2015.

Point Loma Sportfishing – A group of anglers on a Point Loma Sportfishing expedition pose with their bluefin tuna catches, weighing 100 to 200 pounds each, July 29, 2015.

The tropical fish are typically reeled in off Mexico and far off-shore, Dalo said. Now they’re being hooked as close as 10-20 miles off of San Diego, where water temperatures are exceptionally warm.

“Right now we’re 4 to 5 degrees above normal, which to you and me doesn’t seem like much, but if you’re an animal living in the sea and you live at that temperature — that’s a huge change,” said Toby Garfield, director of the Environmental Research Division at Southwest Fisheries Science Center in La Jolla.

The warm water, which scientists have named “the blob,” formed two years ago near Alaska and has spread down the West Coast. Garfield said the warm conditions have sent mother nature into disarray.

“In fact, having this additional warm water has changed the winds a little bit,” Garfield explained. “The upwelling winds really drive the productivity along the California coast. So if you reduce that productivity, you start changing a lot of different parts of the whole ecosystem.”

Much of the fishery population has shifted north, and El Niño hasn’t even arrived yet, said Garfield, who analyzes ocean conditions and reports his findings to the Pacific Fishery Management Council.

“If you go out and do an assessment and you’re not sure where that population is from, you can get some erroneous results in terms of how you’re going to divide up the fisheries,” Garfield said. “And remember, the fish don’t know there’s a Mexican border or Canadian border.”

“We really do have a front row seat on a fascinating change,” Garfield added. “We haven’t seen it this anomalously warm in the record, and at the same time, we’re having a developing El Niño.”

Garfield said he sees two possible scenarios playing out this winter: El Niño’s storm energy will stir up the water, causing the cool water from the ocean depths to mix with and cool the water at the surface.

“That’s one scenario — that it may disappear and will go back to more normal temperatures,” Garfield explained. “The other scenario is that the two will reinforce each other and we’ll have even warmer conditions, and the weather patterns will be different than we expect with a normal El Niño.”

Garfield says additional heat from El Niño could produce storms with higher energy and moisture.

Meanwhile, the telltale signs of current ocean water temperatures from “the blob” have appeared in recent months along San Diego’s shores. The unusual visitors range from hammerhead sharks to tropical fish to millions of red tuna crabs.

“We’ve also seen ‘by the wind sailors’ that have occurred en masse on the shores here on La Jolla and elsewhere,” said David Checkley, a professor of marine biology at Scripps Institution of Oceanography.

Checkley said the reduction in upwelling of cold water nutrients from the ocean floor has drastically altered the food web.

“At the base of the food chain it’s been observed that the amount of chlorophyll or phytoplankton is lower than normal because we have fewer nutrients brought up into the surface waters,” Checkley said.

Phytoplankton provide food for a wide range of sea creatures including whales, shrimp, snails, and jellyfish, according to the National Oceanic Atmospheric Administration.

“The continued poor health of the California sea lion population is likely due to a lack of forage — anchovy, sardines… perhaps squid,” Checkley said.

An algal bloom occurring along the West Coast from California up to Alaska is also a growing concern.

“Those harmful algal blooms sometimes come with toxins — demoic acid that can poison marine mammals that eat fish that consume those algae,” he said.

Checkley said water temperatures will likely eventually return to normal, but he can’t help but look at the conditions as a harbinger of the future.

“What perhaps is worrisome is if you think of things such as this and a long-term trend in a rise in temperatures associated with the climate warming or climate change,” Checkley said.

He predicts some sea creatures will suffer through El Niño.

“The winners are the recreational fishermen,” Checkley said.

San Diego’s sportfishing season usually wraps up in September, but not this year.

“We’re hoping this stuff stays around,” Dalo said. “If it stays up here, we can fish in U.S. waters. You bet. We’ll fish into October. We’ll fish into November.”


This map of the West Coast shows sea surface temperature anomalies in the Pacific Ocean in March 2015. They show how much above (red) or below (blue) water temperatures were compared to the long-term average from 2003 to 2012.

NASA – This map of the West Coast shows sea surface temperature anomalies in the Pacific Ocean in March 2015. They show how much above (red) or below (blue) water temperatures were compared to the long-term average from 2003 to 2012.

Tuna crabs blanket the shoreline at Ocean Beach in San Diego, June 12, 2015. By Susan Murphy – Tuna crabs blanket the shoreline at Ocean Beach in San Diego, June 12, 2015.

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Aug 27 2015

Sea levels will rise, experts warn, and ‘it’s not going to stop’

Aug 19 2015

El Niño, explained: Why this year’s could be one of the strongest on record

NOAA visualization of ocean temperatures for the week of August 10, 2015. NOAA/Environmental Visualization Laboratory


Over the past year, scientists have been keeping a close eye on an important swath of the Pacific Ocean, just along the equator. When conditions here are just right, an El Niño can form — and wreak havoc on weather patterns across the globe.

And right now, it looks like we’re on pace for a very large El Niño this fall or winter. Quite possibly one of the strongest on record. Based on past experience, that could potentially bring much-needed rain in California, but also drought in Australia, destructive floods in Peru, and so on. A strong El Niño could also help make 2015 and 2016 some of the hottest years ever recorded. It’d be a very big deal.

But El Niño events are often unpredictable and full of surprises. So nothing’s guaranteed just yet. What follows is a guide to how El Niño works, what we know about the 2015 event, and how a potentially massive El Niño could upend the world’s weather later this year.

A very basic definition of El Niño

  • El Niño is a weather phenomenon that occurs irregularly in the eastern tropical Pacific every two to seven years. When the trade winds that usually blow from east to west weaken, sea surface temperatures start rising, setting off a chain of weather impacts.
  • El Niños can be strong or weak. Strong events can temporarily disrupt weather patterns around the world, typically making certain regions wetter (Peru or California, say) and others drier (Southeast Asia). Some countries suffer major damage as a result.
  • El Niños also transfer heat stored in the deeper layers of the ocean to the surface. When combined with global warming, that can lead to record hot years, as in 1998.
  • “El Niño” got its name in the 1800s from Peruvian fisherman, who first noticed a mysterious warm current that would appear around Christmas. They called it the “little boy” or “Christ child.”

Why this year’s El Niño could be a huge deal

The last truly massive El Niño appeared in 1997-’98 and ended up causing an estimated $35 billion in destruction and 23,000 deaths around the world. (It also inspired that famous Chris Farley sketch.) Now we may be on the verge of a similar-size event:

Early-August status of the 1997 and 2015 El NIño events in terms of satellite-derived data showing departure from average sea-surface height for a given time of year, which is correlated with warmth in the upper ocean. (<a href="">NASA/JPL</a>)

Early-August status of the 1997 and 2015 El NIño events. Satellite imagery shows the departure from average sea-surface height for a given time of year, which is correlated with warmth in the upper ocean. (NASA/JPL via Weather Underground)

That, in itself, is a surprise. Back in March, NOAA’s Climate Prediction Center announced that a weak El Niño had formed in the Pacific, but many experts initially thought it might just fizzle out in the summer. Instead, El Niño kept getting stronger, with ocean temperatures in the eastern tropical Pacific continuing to soar. Some forecasters now think this could turn into one of the strongest El Niño events in memory when it peaks later this fall or winter.

“We’re predicting this El Niño could be among the strongest El Niños in the historical record, dating back to 1950,” said Mike Halpert, deputy director of the Climate Prediction Center, in a recent press call. We’ll see if this latest forecast holds up.

If it does, countries across the globe will have to brace themselves. In the past, major El Niño events have brought unusually hot, dry weather to Australia that can cramp wheat yields and amp up wildfires. It can bring hotter, drier weather to India that hurts agriculture. It can bring heavy rain and destructive flooding to Peru, washing away houses and spreading cholera. In 1997, El Niño dried out Indonesia so badly that it led to huge forest fires whose smoke disrupted daily life in Singapore.

Yet El Niño isn’t all bad. In the United States, it could potentially bring needed rain this winter to ease California’s drought (though also mudslides and flooding). Historically, El Niño has also served up milder US winters and helped tamp down hurricanes in the Atlantic Ocean.

One important caveat here is that every El Niño is a bit different — and some have unexpected impacts. As NOAA’s Emily Becker points out, strong El Niño events usually bring rain to California (as in 1982-’83), but occasionally they don’t (as in 1965-’66):

El Niños effect on rainfall patterns in the US

(NOAA Climate Prediction Center)

Another story to watch is whether a strong El Niño could help make 2015 or 2016 the hottest year on record. This one seems increasingly plausible.

Global temperatures are already going up over time, thanks to all the carbon dioxide we’re adding to the atmosphere. According to NASA, 2014 was already the hottest year on record. But there was no El Niño that year — and El Niño years tend to be a bit hotter than average, as heat gets transferred from the ocean to the surface. So the combination of El Niño and rising CO2 could help 2015 and even 2016 break records:


Bottom line: There’s still a lot of uncertainty here, but El Niño could very well be the biggest weather story of late 2015, with potentially far-reaching impacts.

How El Niño actually works, step by step

To see how El Niño works, it helps to understand what the equatorial Pacific looks like under normal, or “neutral,” conditions:

1) Neutral conditions in the equatorial Pacific Ocean

Normally, the tropical Pacific features strong trade winds that blow warm ocean water from east to west, where it piles up near Indonesia. Meanwhile, back east along South America, frigid water deep down in the ocean gets pulled up closer to the surface, cooling the area around Peru. Here’s a diagram:

Neutral conditions in the equatorial Pacific Ocean

(William Kessler/NOAA/PMEL)

As a result, during “neutral” conditions, sea levels are about half a meter higher near Indonesia than they are in Peru. And the surface water near Indonesia is about 8°C warmer (14.4°F) than it is near Peru. That temperature difference creates a convective loop in the atmosphere that, in turn, reinforces the trade winds.

This ends up affecting a lot more than just this stretch of ocean. Because the Pacific is so vast, this system is a major driving force in the global climate. The large, warm pool of water near Indonesia causes the air above it to rise, creating rainfall in the region. And this system shapes the jet streams that guide weather and storms around the world.

That’s how it works under normal conditions, anyway. But things look a little different when El Niño comes along.

2) Now along comes El Niño

Every few years, those prevailing Pacific trade winds that blow east to west can weaken. (Scientists are still debating the nuances of exactly why this happens.)

When the trade winds weaken, all that warm water that was piled up near Indonesia starts sloshing back eastward, pulled back down by gravity. What’s more, the underwater layer known as the thermocline starts sinking. As a result, there’s less cold water rising up from the deep ocean near South America — so the waters near Peru start warming up. Here’s another diagram:

El Niño conditions

(William Kessler/NOAA/PMEL)

This causes sea surface temperatures in the east and central Pacific to start rising and the trade winds to weaken even further. What’s more, rainfall starts following that warm pool of water as it travels eastward. That’s why El Niño is usually associated with drier weather in places like Indonesia and Australia, as well as heavier rains in places like Peru (or California). The rain is essentially moving east.

Scientists officially declare an El Niño when sea surface temperatures in the equatorial Pacific Ocean (known as the Niño 3.4 region) rise 0.5°C above their historical baseline for three months in a row — and once atmospheric conditions and rainfall patterns shift accordingly.

Again, because the Pacific is so vast, an El Niño can have large ripple effects on weather around the world, especially during the winter months. Here’s a look at the changes that have historically accompanied El Niño events:

Typical effects of an El Niño during the winter:

Typical effects of El Niño in the winter


A strong El Niño can weaken monsoons in the Indian Ocean, for example. It can also cause the jet stream to start stretching from the Eastern Pacific across the southern United States, bringing rainfall and storms with it. Still, a lot depends on how strong the El Niño actually is — and occasionally there are aberrations and exceptions to the rule. More on that below.

El Niño’s return in 2015 — and why scientists are talking about a “Godzilla” event

Ever since early 2014, scientists have been expecting this latest El Niño to form. But, in a sign of how slippery the system can be, El Niño kept defying predictions and not showing up.

Finally, in March 2015, after a number of false starts, scientists at NOAA’s climate prediction center were ready to declare that a weak El Niño was underway. Specifically, sea surface temperatures in that Niño 3.4 region (roughly in the center of the chart below) had been at least 0.5°C above their baseline since September. And, importantly, atmospheric conditions were responding in turn, with more rain over the central Pacific and less rain over Indonesia:

A weak El Niño emerges in early 2015

Sea surface temperature departures from average (based on 1981–2010) at the end of February 2015. NOAA map by Emily Becker, Climate Prediction Center.

At the time, however, NOAA’s forecasters said that this El Niño looked “weak,” with possibly minimal effects on global weather patterns, and only had a 50 to 60 percent chance of lasting through the summer.

Then, somewhat unexpectedly, El Niño got stronger and stronger. By August 2015, sea surface temperatures had soared to more than 1.2°C above baseline in the Niño 3.4 region, and scientists were seeing the resulting telltale atmospheric changes. Here’s a chart from July and August — notice how the anomalous warm area has moved eastward since March:

Average sea surface temperature anomalies, July/August 2015

Sea surface temperatures in the tropical Pacific: departure from the 1981-2010 average. (NOAA)

NOAA’s Climate Prediction Center is now estimating that there’s a 90 percent chance El Niño will persist through the fall/winter. And when it peaks, signs suggest that this could be an extremely strong event, rivaling the strongest El Niños since detailed records began in 1950. Some forecasters have even dubbed this one a potential “Godzilla.”

Over at NOAA’s ENSO blog, Emily Becker offers a more detailed breakdown of why forecasters are betting on a powerful, possibly record-setting, El Niño. Keep in mind that forecasts often go awry, that surprises occur regularly, and we can’t be perfectly certain of how things will turn out. Still, she writes, “We have a relatively confident forecast for a strong event.”

El Niño could bring rain to California — but may not end the drought

As noted above, El Niño tends to be associated with changes in weather patterns around the world, especially during the Northern Hemisphere winter. The most tantalizing possibility is that a strong El Niño could bring rain to California, potentially alleviating the state’s drought.

But even here, nothing is yet assured. El Niño only affects US weather indirectly, by altering atmospheric circulation and shifting the North Pacific jet stream. (See here for a lucid explanation by Columbia University’s Anthony Barnston.) This is an intricate chain of events, and small kinks at certain points can affect the ultimate outcome.

As such, Becker cautions people to think not in terms of certainties but in terms of probabilities. Here’s an example of how El Niño might shift the odds of a wet winter for California (she notes that this isn’t a prediction, just an illustration):

How El Niño shifts the odds of

An example of how a strong El Niño could shift the odds for the amount of seasonal precipitation. Official outlooks from the Climate Prediction Center are available here.

In other words, thanks to El Niño, California has a greater chance of more precipitation this winter, but not a 100 percent chance.

What’s more, even if rain does come, that may not be enough to completely erase the massive water deficit that California has built up over the past five years. The state likely needs record precipitation to end the drought, and it also needs the right mix of rain (to recharge the reservoirs) and snow in the Sierra Nevada mountains (to melt during the spring and summer).

Also, be warned: Heavy rain after a drought can bring floods and mudslides. So California needs to be ready for some negative impacts, as well.

El Niño tends to hurt some countries, and benefit others

It’s not quite right to say that El Niño events are “bad” or “good.” They tend to have different impacts on different regions.

One recent study from the University of Cambridge found that on average, El Niño events hurt economic activity in Australia, Chile, Indonesia, India, Japan, New Zealand, and South Africa. The reasons varied: drought and reduced crop yields in Australia and India, forest fires in Indonesia, less-productive fisheries in Peru.

But that study also found that on average, El Niño tends to boost the economies in Argentina, Canada, Mexico, and even the United States, at least in the very short term. Again, many factors were at play: In addition to bringing needed rain to California and Texas, El Niño was associated with less tornado activity in the Midwestern United States and fewer hurricanes in the Atlantic Ocean.

Here’s a table of the estimated economic impacts on a broad selection of countries:

Economic effects of El Niño

(Cashin et al, 2014)

Again, every big El Niño is different and has its own idiosyncrasies. So think of this table as more a rough guide than gospel.

El Niño could help make 2015 or 2016 the hottest years on record

Thanks to global warming, the Earth’s average surface temperature has been going up over time. But there’s a lot of variation from year to year. El Niño years tend to be a bit hotter than average. La Niña years (when those trade winds strengthen rather than weaken) tend to be a bit cooler than average. Like so:

El Niño years are hotter than average


So what’s going on here? As humans load more greenhouse gases in the atmosphere, we’re trapping more and more heat on the Earth’s surface. But more than 90 percent of that extra heat is absorbed by the oceans. So subtle interactions between the ocean and the atmosphere can make a big difference for surface temperatures.

When conditions in the Pacific are neutral, more of that heat is trapped beneath the ocean surface. When a strong El Niño forms, more of that heat is transferred to the surface. That’s why the Earth’s average surface temperatures reached new highs in 1998: you had the combination of global warming and an extremely strong El Niño.

What was remarkable about 2014 is that it was likely the hottest year on record even without an El Niño event — a sign that Earth keeps getting warmer overall. Meanwhile, 2015 has so far been on track to be even hotter than 2014.

Now throw a potentially record-setting El Niño into the mix, and we’re looking at a potential shattering of records. Back in January, NASA’s Gavin Schmidt explained at a press conference that temperatures typically peak about three months after an El Niño event. Given that forecasters expect this current El Niño to last until next spring, it’s entirely possible we could see 2015 or 2016 break the temperature record. We’ll have to wait and see.

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Aug 14 2015

Forget El Niño, the ‘PDO’ could be the real drought buster

110103-fullAn image showing the positive / warm phase of a PDO and the negative / cold phase. The terms warm and cold refer to the temperature of water off the west coast of America. JPL/NASA


A new forecast out Thursday on the El Niño climate pattern shows it could be one of the strongest on record. And that could deliver much needed rain to Southern California and possibly northern parts of the state, too. But El Niños are usually fleeting, lasting only a year or two.

Now, evidence is building that a longer-term climate pattern — one that might bring years of rainy winters — could be forming in the Pacific well north of the equatorial waters that give rise to El Niño.

The PDO game change

For the past several months, researchers have been tracking warmer temperatures in this northerly patch of ocean. And they’re beginning to question whether we’re about to see a switch in something called the Pacific Decadal Oscillation or PDO.

Given the data, the PDO could be shifting from a cool phase to a warm one — a shift that could mean a wetter decade ahead for much of California. Still, the phenomenon could also turn out be a short-lived blip, not a years-long flip.

Unlike El Niño, which focuses on sea surface temperatures in a stretch of the Pacific near the equator, the PDO looks at water in the northern part of the ocean, from Hawaii all the way to Alaska.

According to research scientist Nathan Mantua with the National Oceanic and Atmospheric Administration, the PDO has a warm phase and a cool phase, and each one can last anywhere from a few years to decades.

During the warm phase, waters along the coast of the western U.S. tend to heat up while the larger ocean about 200 miles off the coast cools down. During the cool phase these trends are reversed.

“When you have the warm pattern of the PDO, it tends to be wet in the southwest U.S. and northern Mexico,” he explained.

During those same years you are more likely to see drought in the Northern Rockies, Idaho, Eastern Washington, Western Montana and Southern British Columbia.

Likewise, the cool phase is linked to wetter periods up north but dry conditions in Southern California and neighboring states.

Mantua says the PDO has been mostly in a cool phase since 1998, coinciding with some of California’s driest years on record.

Climate scientist Bill Patzert with the Jet Propulsion Laboratory thinks it’s this PDO pattern that is responsible in large part for the severe drought in the region.

Long-term drought buster on the horizon?

However, since January of 2014, the PDO has been shifting into a warm mode.

Patzert thinks this could be the drought-buster the state has been hoping for.

“Perhaps in the long term, rooting for a [warm] PDO… is probably the most important thing for California and the American West,” he said.

Thursday and Friday at JPL’s von Kármán Auditorium, Patzert will give a free public lecture on the PDO, El Niño and drought.

He said even a strong El Niño isn’t likely to supply all the water needed to get California out of a drought this bad.

In fact, a recent NASA study found the state would need double the average rainfall in a single year to break the drought.

“In the long run these decadal or multi-decade variations in the Pacific are really the key to sustaining California agriculture and California civilization,” Patzert said.

That may be true for Southern California, but it is less clear how a warm PDO will affect Northern California, said NOAA’s Nathan Mantua.

That’s because the northern part of the state is between the two regions that switch from wet and dry as the PDO shifts.

“Northern California sort of sits between the ends of this sort of north-south see-saw,” he said.

Still, he’s optimistic that a warm PDO is coming, since the major index predicting this pattern has been positive for 19 months.

But Mantua cautions that even such a strong signal can result in a warm PDO that only lasts a year or so.

“Beyond that, it’s going depend on what the winds do and the weather patterns,” he said.

Sometimes those can change rapidly and dramatically, bringing drought conditions anew to California.

Another wild card, according to JPL’s Patzert, is how climate change will affect the PDO and related weather patterns.

“As we move into the 21st Century, climate is shifting beneath our feet… nobody really understands what the impact will be,” he said.

For now, climate watchers will keep their eyes on the ocean for signals of the weather to come.

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Aug 11 2015

Possible Spoiler for El Niño: A ‘Battle of the Blobs’


Hopeful Californians are looking to the Pacific this winter for an end to California’s most punishing drought on record.

The reason: what appears to be a monster El Niño in the making. The abnormally warm waters along the equator could mean a wet winter.

There are no guarantees, but there have been portents. On one Saturday in July, San Diego got more rain than it got the entire month of January.

That same month, ESPN broadcaster Dan Shulman broke the news to baseball fans from underneath a golf umbrella: “For the first time in 20 years, a game has been postponed because of rain here in Anaheim.”

You can thank Dolores for that, a hurricane that managed to make it farther north than normal. The intense Pacific hurricane season bears the fingerprints of El Niño, which is already getting hyped as a potential drought-buster.

“Yes, and deservedly so,” says Kevin Trenberth, a Distinguished Senior Scientist at the National Center for Atmospheric Research in Boulder, Colorado.

“For this time of year, the El Niño is as strong as it’s ever been.”

Ridiculously-Reilent-Ridge-graphic-e1422040126985-1024x629Storms headed for the California coast run into the Ridiculously Resilient Ridge, represented by the “H” in this graphic. (David Pierce/ KQED) 

Strength in this case is measured by how much warmer surface temperatures are than normal, in the tropical Pacific. And this one looks to be about as strong as the legendary El Niño of 1997-98, which was the strongest on record, peaking at about 2.3 degrees Celsius above normal.

In the ocean, a spike of more than two degrees is like sticking a hot poker into the climate system. Pacific storms sucked up moisture from extremely warm equatorial waters and pretty much dumped it on California. San Francisco got double its normal rainfall that year.

Enter the Blob

But this time around, there are other things brewing in the Pacific: patches of freakishly warm water spread far and wide, up the California coast to the persistently warm vortex, hundreds of miles across, christened by climate scientists as “the Blob.”

“That is definitely the wildcard with this El Niño,” warns Bill Patzert, a climatologist at NASA’s Jet Propulsion Lab in Pasadena and an advisor to federal El Niño forecasters.

He says unlike in 1997, the Blob has been a fixture during the current drought. It’s essentially the sidekick of that “Ridiculously Resilient Ridge,” the stubborn bubble of high-pressure that’s been parked off the north coast for the past couple of years, diverting winter storms up and around California.


The “Blob” is associated with the persistent ridge of high pressure that has detoured the winter storm track around California. (NOAA)

“And so the question is, who wins in the battle of the Blob and the El Niño,” says Patzert, “and what impact that’ll have on rainfall on the West Coast of the U.S. this fall, into the winter.”

Patzert says if the Blob and its ridge dominate, we could wring less water out of this El Niño.

“What we’re having here is battling blobs!”

But not everyone’s on the edge of their seat.

“It doesn’t fit with my concept of how things work,” says Trenberth. On the contrary, he maintains, the presence of all this warm water — especially close to the coast — could mean heavier rains from the storms we do get.

A Mixed Blessing

“The potential in California for rains to be torrential this winter is quite high because of the warm water,” Trenberth says.

That’s because, as a general rule, the warmer the water, the more moisture gets picked up by the atmosphere and by any emerging storms.

Weather-west-imageOcean waters near California have warmed further in recent weeks, and remain far above normal. (NOAA RTG)

“Those storms are apt to pick up moisture from any warm water that’s lying around all along the West Coast,” says Trenberth, “and it just feeds those storms.”

That would be both good and bad news. While the reservoirs refill, the rivers could easily overfill, causing flooding and landslides — much like in 1997-98. Trenberth will take that glass as half-full.

“The way things are shaping up it sure looks like an end to the drought to me,” he says, “depending on how you define the drought.”

Patzert agrees the current El Niño is looking like a monster — “Godzilla,” to use his favorite moniker. But he’s concerned the Blob and its ridge could become at least partial spoilers, blocking out storms from the northern Pacific, leaving the door open only for El Niño-driven storms from the tropics.

That could mean Southern California gets a soaking, but the northern part of the state — where most of the major reservoirs are — misses out.

“There is almost certainly going to be a dividing line,” says Stanford climate scientist Daniel Swain. “And it’s possible that dividing line could occur somewhere in Northern California.”

Patzert hopes that isn’t the case.

“If that happens, I’m definitely going to have to go into witness protection,” he frets, “because ‘my’ El Niño, the Great Wet Hope, will only deliver half the package.”

Whatever we get, it’s a package that won’t be delivered for at least three months, when California’s long-awaited “rainy” season is due.

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Jul 9 2015

El Nino Impacts Could be Among Strongest Ever, Stretch Into 2016 After Series of Cyclones

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

Copyright © 2015

Seafood News


The El Nino climate pattern building in the Pacific is on track to be one of the strongest on record, with recent cyclones likely to intensify the event, the Bureau of Meteorology said.

Sea-surface temperatures in the central equatorial Pacific in June recorded the second largest anomalies on record for the month, behind only the June 1997 reading during the super 1997-98 El Nino event, the bureau said in its latest update.

Weekly sea-surface temperatures were also more than 1 degree above average for each of the regions monitored, their warmest sustained values since the 1997-98 event.

A string of tropical cyclones, including the rare July southern hemisphere storm, Cyclone Raquel, mean the El Nino will likely strengthen in coming weeks as “a strong reversal of trade winds” near the equator takes place.

“This is likely to increase temperatures below the surface of the tropical Pacific Ocean, which may in turn raise sea-surface temperatures further in the coming months,” the bureau said.

Unlike the last few El Ninos, the eastern Pacific is particularly warm, much like the “canonical” events of 1982-83 and 1997-98, Lynette Bettio, a senior climatologist with the bureau said. Model projections also have the event lasting well into next autumn.

The Southern Oscillation Index, which measures the pressure difference between Darwin and Tahiti, had also dropped sharply in recent weeks, one gauge watched closely by farmers worried about the rainfall outlook, she said.

El Ninos are characterised by central and eastern parts of the Pacific warming relative to those in the west. One result is that the normally easterly trade winds slow or reverse, with rainfall patterns tending to shift eastwards away from eastern Australia and south-east Asia.

Cool patch coming

While global temperatures tend to be boosted by El Ninos, the pattern does not mean all regions are warmer than usual for the event’s duration.

Australia, for instance, is about to enter a relatively cool patch mostly as a series of powerful cold fronts from the south penetrate unusually far to the north.

The first of them should move across south-eastern Australia on Friday and Saturday, and “is going to be the coldest front of the year”, Tristan Meyers, a meteorologist at Weatherzone, said.  (See below for Sunday’s synoptic chart.)

Temperatures will be noticeably cooler in Melbourne, with the maximum dropping from 15 degrees on Thursday to 11-13 from Saturday to Tuesday. In Sydney, relatively mild maximums of 19 degrees on Friday and Saturday will retreat to 15 degrees by Sunday.

“We’re going to see some frost up in south-east Queensland,” Mr Meyers said.

Towns such as Stanthorpe will likely have a top of just 8 degrees on Sunday and Monday, with overnight lows of minus-2 to zero, according to the bureau.

While the front as a while won’t be bringing a lot of rain, the ski resorts should receive another 10 centimetres or so of snow to boost their thin natural cover, Mr Meyer said, adding that more fronts won’t be far behind.


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Jul 6 2015

Strong Westerlies Push El Nino Toward Extreme Event

For the past two weeks, winds have been blowing in an anomalous west-to-east pattern across the Western Pacific. It’s the third such pattern since El Nino conditions began to become more prevalent during March of this year. And forecast model response to the most recent westerly wind burst is an overall shift toward predicting a record event. Models are starting to settle on at least a strong El Nino come fall (1.5 degree Celsius anomaly or greater for Nino 3.4) with many ensembles predicting something even more intense than the super El Nino of 1998.

This third, El Nino heightening, westerly wind burst (WWB) coincided with a strong, wet variation of the Madden Julian Oscillation pumping up thunderstorm activity throughout the region. Last week, a consistent 20-35 mph westerly wind pattern had become very well established. Over the past four days, multiple cyclones became embedded within the pattern, which now stretches over 3,000 miles in length, pushing locally stronger winds and reinforcing the already significant wind field.

By today four cyclonic systems, including Typhoon Chan-Hom, had further heightened westerly wind intensity:


(The current strong westerly wind burst is looking more and more like the extreme event of early March of this year. It’s the third such event — one that is increasing the likelihood that the 2015 El Nino will be one more for the record books. Image source: Earth Nullschool.)

It’s a pattern that in today’s map looks very similar to the record event which occurred this Spring. And it’s the third significant WWB to initiate since March of this year.

WWBs push warm surface water in the Western Pacific downward and across the ocean (read more about how WWBs affect El Nino severity here). These warm water pulses traverse thousands of miles, finally resurfacing in the Eastern Pacific off South America. The resultant warming of surface waters there and through the mid ocean region tends to set in place ocean temperature and atmospheric patterns that reinforce El Nino — driving more westerly winds and still more warm water displacement eastward.

Three westerly wind bursts firing off since March of 2015 have pushed increasingly strong El Nino conditions. A warming of the Equatorial Pacific that, in combination with a massive and rapidly growing greenhouse gas overburden from human fossil fuel burning, is forcing  global temperature readings to hit new record high after new record high.

Nino 3.4 CSV2

(CFSv2 Model runs are pointing toward a very powerful anomaly come Fall. Image source: Climate Prediction Center.)

This third strong westerly wind burst appears to have again pushed model forecasts into very extreme ranges for Fall of this year. NOAA’s CFSv2 ensembles now predicts a peak sea surface temperature anomaly in the range of 2.5 degrees Celsius above average to 3.1 degrees Celsius above average. An El Nino of this strength would be significantly stronger than the monster event of 1998. One that would occur in a global context that includes an approximate 45 parts per million CO2e worth of heat trapping gas accumulation since that time. One that is now in the range of 1 C warming above 1880s averages (or 1/4th the difference between now and the last ice age, but on the side of hot).

Since we are now well past the spring predictability barrier, these new model runs have a higher potential accuracy. That said, we are still four months out and a number of additional factors would have to come into play to lock in such a powerful event. However, the trend is still for a strong to extraordinarily powerful El Nino. And since such an event is occurring in a record warm atmosphere and ocean environment (due to human-caused climate change), the continued potential for related additional anomalous weather events (drought, flood, wildfires, extreme tropical cyclones in the Pacific, etc) is also high enough to remain a serious concern.

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Jun 12 2015

El Niño continues to build, raising chances of wet winter

Gino Celli inspects wheat nearing harvest in May on his farm near Stockton. Moving to meet voluntary water conservation targets, dozens of farmers in the Sacramento-San Joaquin River Delta submitted plans to the state saying they intend to plant less thirsty crops and leave some fields unplanted amid the relentless California drought, officials said. AP Photo — Rich Pedroncelli


In a promising trend that increases the likelihood of steady storms this winter that could ease California’s historic drought, federal scientists on Thursday reported that El Niño conditions in the Pacific Ocean are continuing to grow stronger.

The probability of an El Niño — defined as warmer water at the equator and shifting winds that can bring major weather changes — being present through the end of 2015 is now 85 percent, up from 80 percent last month, and 50 percent three months ago, according to the National Oceanic and Atmospheric Administration.

“The big takeaway is that obviously El Niño has strengthened,” said Mike Halpert, deputy director for NOAA’s climate prediction center in College Park, Maryland.

“We are more confident that it is going to last through the rest of the year, and at this point, we’re slightly favoring a strong event.”

Most important: Trade winds are shifting in ways consistent with prior big El Niños, and sea surface temperatures in the Pacific Ocean near the equator are now 2 degrees Fahrenheit warmer than average in all five zones that El Niño researchers study, a trend not seen since 1997 when a California was hit was drenching rains and floods the following winter.

To be sure, there are still six months before California’s winter rainy season. Many of those are expected to be brutally dry and hot summer months, with high fire risk. And scientists say promising El Niños have fizzled out in the past, most recently last year.

“El Niño is a bad boy, and sometimes he disappoints. He could abandon us at the altar. It’s not a sure thing at this point,” said Bill Patzert, a research scientist and oceanographer at NASA’s Jet Propulsion Laboratory in Pasadena.

“But it’s probably a good idea to clean out the flood control channels in preparation for January.”


Water Warning

California water officials have worried that news of a building El Niño could cause state residents to ease off water conservation. That could cause emergency shortages next year if El Niño doesn’t deliver a very wet winter, they note, given the state’s low reservoirs, depleted groundwater, rainfall deficits and non-existent snowpack after four years of historic drought.

“Very few of us would empty our bank accounts today on the hopes of hitting the lottery next winter,” said Doug Carlson, a spokesman for the state Department of Water Resources. “And in the same vein, we can hope for rain, but we have to continue to conserve today.”

In recent months, unusual weather patterns have been linked by some researchers to the growing El Niño in the Pacific.

Two weeks ago, torrential storms battered Texas, killing more than 20 people, sending rivers raging over their banks and trapping thousands of people in flooded cars around Dallas and Houston. On May 25, Houston received a stunning 11 inches of rain in one night. By comparison, San Jose has received 13 inches in the past eight months, and Los Angeles 8 inches over the same time period.

That series of storms, which largely ended an ongoing drought in Texas, was caused when the sub-tropical jet stream moved north from Central America, a condition consistent with strong El Niño conditions, experts say.

“You are seeing flooding in Northern Mexico, which is normally very dry, and extreme drought in Nicaragua, which is normally very wet, which are characteristics of El Niño,” Patzert said.

Researchers stress that not all El Niño years bring big rains to California.


Ocean Water

Generally speaking, the warmer the ocean waters are during El Niño years, the greater the likelihood of heavy winter rains in California. During mild El Niño years, when the ocean water is only slightly warmer than historic averages, there are just as many dry winters in California as soaking ones.

Since 1951, there have been six winters with strong El Niño conditions. In four of them, rainfall from the Bay Area to Bakersfield was at least 140 percent of the historic average, according to studies by Saratoga meteorologist Jan Null.

But in the 16 winters since 1951 when there was a weak or moderate El Niño, California experienced below-normal rainfall in six of them, average rainfall in five and above-normal rainfall in the other five.

The term El Niño — or “little boy” in Spanish — was originally used by fishermen off Ecuador and Peru to refer to “the Christ child” because the warming ocean conditions appeared around Christmas every three to eight years.

Typically, El Niños begin when trade winds that normally blow westward, toward Asia, weaken, and then blow the other way. That allows warm ocean water near the equator to spread east, toward South America. Rainfall follows the warm water, which can mean wet winters for California, Peru and other areas, and droughts in Australia.

The opposite, or cooling ocean water, is a “La Niña.”



With each month that draws closer to California’s winter rainy season, forecasts become more reliable.

Currently, an ocean area that scientists call the “3.4 region” along the equator near South America that is considered a key indictor of El Niño trends is 1.2 degrees Celsius, or 2.1 degrees Fahrenheit, above the historic average. That departure from normal is twice what it was a year ago.

And the trend is expected to keep growing.

Supercomputers at NOAA, NASA and other world-leading scientific institutions are projecting the temperatures in that ocean region to hit 1.6 degrees Celsius, or nearly 3 degrees Fahrenheit, on average by September. The last time temperatures there reached that level in a September was in 1997, when they hit 2.3 degrees Celsius, or 4.1 degrees Fahrenheit, above average.

What followed was among the wettest winters in California history, similar to another strong El Niño year, 1982-83, with California receiving twice as much rain as normal. In February 1998, four weeks of storms and powerful winds led to mud slides and widespread flooding that killed 17 people and caused 35 California counties to be declared federal disaster areas from the Napa Valley to the Southern California coast.

“Be careful what you wish for,” said Patzert.

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