Is El Niño Developing?

Data from ocean-observing satellites and other ocean sensors indicate that El Niño conditions appear to be developing in the equatorial Pacific Ocean. Conditions in May 2014 bear some similarities to those of May 1997, a year that brought one of the most potent El Niño events of the 20th century.

During an El Niño, easterly trade winds in the Pacific falter and allow giant waves of warm water—known as Kelvin waves—to drift across from the western Pacific toward South America. Surface waters in the central and eastern Pacific become significantly warmer than normal, altering weather patterns and affecting fisheries along the west coasts of the Americas. El Niño also can have a significant influence on weather and climate far from the tropics.

The maps above show the ten-day average of sea surface height centered on May 2, 1997 (left), and May 3, 2014. Shades of red and orange indicate where the water is warmer and above normal sea level. Shades of blue-green show where sea level and temperatures are lower than average. Normal sea-level conditions appear in white. The 1997 map was assembled from data collected by the TOPEX/Poseidon satellite, while the 2014 data comes from the Ocean Surface Topography Mission/Jason 2 satellite.

The height of the sea surface is a good indicator of the amount of heat stored in the water. As the ocean warms, the surface rises; as it cools, its falls. This is due to thermal expansion and contraction; the molecules in warmer water are farther apart than in cooler water. Above-normal sea surface heights in the equatorial Pacific indicate El Niño conditions, while below-normal heights indicate La Niña. (You can see an example of La Niña here and El Niño here.)

“What we are now seeing in the tropical Pacific Ocean looks similar to conditions in early 1997,” said Eric Lindstrom, oceanography program manager at NASA headquarters. “If this continues, we could be looking at a major El Niño this fall. But there are no guarantees.” Observations from a network of sensors within the Pacific Ocean support the satellite view, showing a deep pool of warm water that has been sliding eastward since January.

The years 1997–98 brought El Niño out of the scientific literature and onto the front pages and evening newscasts. It was one of the strongest El Niño events observed, with extreme weather impacts on several continents. North America had one of its warmest and wettest winters on record, particularly in California and Florida. Peru, Mexico, and the rest of Central and South America endured devastating rainstorms and flooding. Indonesia and parts of Asia saw disastrous droughts.

Scientists at the Climate Prediction Center of the National Weather Service (NWS) announced on May 8 that they foresee a 65 percent chance of a transition to El Niño in the summer of 2014. “There remains uncertainty as to exactly when El Niño will develop and an even greater uncertainty as to how strong it may become,” NWS reported.

“If El Niño returns, the American West and Southwest could see major relief next winter from the long-lasting, punishing drought,” said climatologist Bill Patzert, who has been studying El Niño via satellite for two decades from NASA’s Jet Propulsion Laboratory. “Further, the very frigid winter in the upper tier of the U.S this past winter could do a flip to mild next winter.”

1. References and Related Reading

2. Jet Propulsion Laboratory (2014) Historical El Nino/La Nina Watch. Accessed May 13, 2014.
3. NASA Earth Observatory World of Change: El Nino, La Nina, and Rainfall.
4. National Weather Service: Climate Prediction Center (2014, May 8) El Nino/Southern Oscillation Diagnostic Discussion. Accessed May 13, 2014.
5. NOAA Climate Watch (2014, April 25) Slow slosh of warm water across Pacific hints El Nino is brewing.

Data courtesy NASA JPL Ocean Surface Topography Team. Maps by Marit Jentoft-Nilsen and Robert Simmon. Caption by Michael Carlowicz.

Instrument(s): 

JASON-2 - NASA

Ocean Temperatures Reach El Niño Threshold; El Niño Odds Rise Above 65%

For the first time since the fall of 2012, weekly-averaged sea surface temperatures (SSTs) in the equatorial Pacific have reached the threshold needed for an El Niño event to be declared. By definition, an El Niño episode occurs when SSTs are at least +0.5°C from average for three consecutive months in the region 120°W - 170°W, 5°S - 5°N (called the Niño 3.4 region.) The weekly ENSO update issued by NOAA on May 12, 2014, put ocean temperatures in this Niño 3.4 region for the past seven days at +0.5°C from average. An El Niño event is still not a sure thing, though. We saw similar behavior in the fall of 2012, with SSTs warming up above the +0.5°C threshold, prompting NOAA to issue an El Niño Watch. However, the ocean SSTs were not able to hold for the required three month period, and no El Niño event ended up happening. However, this year the odds appear more favorable. NOAA has issued an El Niño Watch for the summer and fall of 2014, giving a greater than 65% chance that an El Niño event will occur during summer, a boost upwards from their >50% chance given the previous month. The May 8 El Niño discussion from NOAA's Climate Prediction Center noted that "There remains uncertainty as to exactly when El Niño will develop and an even greater uncertainty as to how strong it may become. This uncertainty is related to the inherently lower forecast skill of the models for forecasts made in the spring." None of the El Niño models (updated in mid-April 2014) predict La Niña conditions for peak hurricane season, August-September-October 2014, and 16 of 20 predict El Niño conditions. There is currently not a strong Westerly Wind Burst (WWB) over the equatorial Pacific Ocean helping push warm water eastwards towards South America. There have been three of these WWBs so far in 2014, and if we get one more in the next month or two, that should be enough to push the system into a full-fledged El Niño event.

Figure 1. Departure of sea surface temperature (SST) from average for May 12, 2014. A plume of warmer-than-average temperatures stretched along the equatorial Pacific from the coast of South America westwards into the Western Pacific, a harbinger of a developing El Niño event. Image credit: NOAA.

El Niño events usually lead to quiet Atlantic hurricane seasons
El Niño conditions tend to make quieter than average Atlantic hurricane seasons, due to an increase in upper-level winds that create strong wind shear over the Tropical Atlantic. The last official El Niño event occurred from summer 2009 - spring 2010, and as expected, the 2009 Atlantic hurricane season was a relatively quiet one, with 11 named storms, 3 hurricanes, and 2 major hurricanes. No 2009 hurricanes got their names retired, and there were only six fatalities.

NOAA Launches ENSO Blog
Just in time for the likely arrival of El Niño comes the new NOAA ENSO Blog (ENSO is the acronym for “El Niño - Southern Oscillation”, which is the more scientifically rigorous term for what I typically refer to as “El Niño.") The blog is written by a team of three veteran El Niño scientists:

• Anthony (Tony) Barnston, chief forecaster at the International Research Institute (IRI) for Climate and Society
• Emily Becker, a researcher at the NOAA’s Climate Prediction Center (CPC)
• Michelle L’Heureux, who has led the team in charge of routinely producing NOAA/NWS/CPC’s ENSO updates and outlooks since 2006

They have not yet enabled comments, but they expect to do so within the next week or two. I look forward to seeing their expert commentary.

Jeff Masters - Wunderground

Warm water in Pacific could spark a monster El Nino in 2014

Scientists are watching a giant mass of sub-surface water in the Pacific. When this water reaches the sea surface, it could set off a powerful El Nino.

The giant red blob in this image is a huge, unusual mass of warm water that currently spans the tropical Pacific Ocean. Eric Holthaus, a meteorologist who writes about weather and climate for Slate, says the volume of water is big enough to cover the United States 300 feet deep. And that’s a lot of warm water, he says. Holthaus also says that, as the sub-surface warm water in the Pacific moves eastward – propelled by anomalous trade winds – it’s getting closer to the ocean’s surface. Once the warm water hits the sea surface, it will begin to interact with the atmosphere. Why? Because Earth’s oceans and atmosphere are always interacting. In this case, the warm water will likely boost temperatures and change weather patterns … and possibly bring on a monster El Nino in 2014. There are signs this is already beginning to happen. Read more at Slate.

Here is a 4-month sequence showing unusually warm water, below the surface of the Pacific Ocean, in the area of Earth’s equator. Via Australian Government Bureau of Meteorology

By the way, the warm water just below the ocean’s surface this year is on par with that of the biggest El Niño ever recorded, in 1997-98. That event caused $35 billion in damages and was blamed for around 23,000 deaths worldwide.

Bottom line: Scientists are watching a giant mass of sub-surface water in the Pacific. When this water reaches the sea surface, it could set off a powerful El Nino in 2014. - EarthSky