Skip to main content

February 2019 ENSO Update: El Niño conditions are here

After several months of flirting, the tropical Pacific ocean and atmosphere appear to have coupled just in time for Valentine’s Day and now meet the criteria for El Niño conditions. Is it true love? Time will tell, but forecasters expect weak El Niño conditions to persist through the spring.

Say yes

For a few months now, the tropical Pacific has met the first two criteria of our “Is It El Niño Conditions?” decision tree.

Schematic of the decision steps for declaring El Niño

Summary of NOAA decision process in determining El Niño conditions. NOAA Climate.gov drawing by Glen Becker and Fiona Martin.

That is, the sea surface temperature in the Niño3.4 region of the tropical Pacific Ocean has been more than 0.5°C above the long-term average, and models were predicting it would stay that way for the next several seasons.

Graph of monthly sea surface temperature Nino 3.4 Index values

Monthly sea surface temperature in the Niño 3.4 region of the tropical Pacific for 2018 (purple line) and all other El Niño years since 1950. Climate.gov graph based on ERSSTv5 temperature data.

What’s new over the past month is that we’re seeing signs of El Niño-related changes in the atmosphere, with increased clouds and rain in the central Pacific indicating a weaker Walker circulation. One measurement of the strength of the Walker circulation, the Equatorial Southern Oscillation Index, was -0.6 during January, indicating more rising air than average over the eastern Pacific, and less than average over the western Pacific. These changes are enough evidence that the atmosphere is responding to the warmer ocean, leading us to conclude we have El Niño conditions!

Be Mine

The Walker circulation—the atmospheric circulation over the whole tropical Pacific Ocean—is usually driven by intense rising air over the very warm waters of the far western Pacific and Indonesia. This air rises to the upper atmosphere, travels eastward, sinks over the eastern Pacific, and travels back westward near the surface, forming the trade winds.

When El Niño’s warmer-than-average surface waters develop in the central-eastern Pacific, the Walker circulation is weakened. The extra heat in the ocean surface warms the air above it, leading to more rising motion, and hence more clouds and rain than average over the central-eastern tropical Pacific. Adding a source of rising air over the central-eastern Pacific, and reducing the rising air over the far western Pacific, means the steady upper-level and near-surface winds are disrupted. Those weaker-than-average near-surface winds in turn help to keep the surface warmer, in a feedback process critical to the coupled system of El Niño.

Call me

The surface warming in the Niño3.4 region is currently just a few tenths of a degree above the El Niño threshold (0.5°C warmer than average), and actually decreased through January. Most of the climate models predict that the surface temperature anomaly (the difference from the long-term mean) will increase slightly in the near future, and remain above the El Niño threshold through the spring.

Graph of NMME monthly forecasts, February 2019

Climate model forecasts for the Niño3.4 Index. Dynamical model data (purple line) from the North American Multi-Model Ensemble (NMME): darker purple envelope shows the range of 68% of all model forecasts; lighter purple shows the range of 95% of all model forecasts. Statistical model data (dashed line) from CPC’s Consolidated SST Forecasts. NOAA Climate.gov image from CPC data.

Bolstering forecasters’ confidence that short-term surface warming will rebound and then persist for the next few months is the presence of warmer-than-average water below the surface of the Pacific. This blob, a downwelling Kelvin wave, will travel eastward over the next few weeks, gradually rising and providing a source of warmer waters to the surface.

Animated image of equatorial subsurface temperature anomalies

Departure from average of the surface and subsurface tropical Pacific sea temperature averaged over 5-day periods starting in early June 2018. The vertical axis is depth below the surface (meters) and the horizontal axis is longitude, from the western to eastern tropical Pacific. This cross-section is right along the equator. Climate.gov figure from CPC data.

U R Cute

But what does it all mean? Is this relationship built to last? The future remains to be seen, but forecasters give weak El Niño conditions the edge through the spring. After that, chances of a continued El Niño drop below 50%. It’s tough to make a successful forecast for later in the year, due in large part to the “spring predictability barrier,” a notoriously tricky obstacle for computer models. Spring is a time of year when ENSO (El Niño/Southern Oscillation, the entire El Niño and La Niña system) is often transitioning, making it especially difficult to predict what comes next.

Weak El Niño conditions means that El Niño isn’t dominating the global circulation, and there is a lower probability of El Niño-related global temperature and precipitation effects through the next few months. Other players, including the Madden-Julian Oscillation, may continue to affect weather patterns. For a prediction of the U.S. climate this spring, check out the Climate Prediction Center’s outlook. For all the ENSO information your heart desires, stick with us!

Comments

Permalink
This subtle El Nino pattern has been present since September. And now you announce the El Nino on Valentines day? But the Winter weather is more complicated than just the influences of the El Nino. There are a couple events going on here. First the MJO was ignored for the winter weather and the East Coast. The Number showed warm weather for the Eastern US. Then the Polar Vortex split and the weak daughter was over Canada and ran out of cold in the Mid West. And the Stronger daughter was in the Barents area and caused the storms that were in Alaska and the storm energy that moved to Hawaii. While the El Nino has the two Jet streams split moving across the US running the storms off the West Coast and the other Jet Blocking the storms off from the East Coast. And if you look closely at the satellite you can see the warmer red spots off the east coast. Weather is more complicated that just El Nino.

Submitted by ALEX KALMAN on Sat, 02/16/2019 - 00:19

Permalink

Hi Alex,

The eastern tropical Pacific has been warmer than normal and even above the minimum threshold for El Nino since fall, but the atmospheric conditions have not been consistent with El Nino until more recently (stay tuned for more on this topic in the next blog post!).  Regarding your comment about weather being more complicated than El Nino, there is no argument here!  As we noted in our Winter Outlook post, we expected other drivers like the Madden-Julian Oscillation and Arctic Oscillation to play important roles in our winter weather this year, both those drivers are much more difficult than ENSO to predict several months in advance.   

Submitted by Nathaniel.Johnson on Mon, 02/18/2019 - 10:10

Permalink
Did the elnino already happen in December and the first two weeks of January?

Submitted by phil.j.janowsk… on Sat, 02/16/2019 - 13:15

Permalink

By December we had fulfilled all the criteria for El Nino in the decision tree except the very last one - we did not see atmospheric conditions consistent with El Nino, like a clearly weakened Walker circulation or enhanced rainfall near the dateline.  At some point between the January and February ENSO Outlooks, the atmospheric conditions became more clearly consistent with El Nino conditions.  That is why the El Nino Advisory was not declared until this month.  

Submitted by Nathaniel.Johnson on Mon, 02/18/2019 - 10:17

Permalink
Is it possible the heat source for the Pacific blob, or subsurface temperature anomalies is geothermal, undersea Volcanoes, and Hydrothermal vents? Seems like an increase in volcanic activity world wide. What do you think the long term trend is for the North Pacific water temp? 42F surface temp right now in the Gulf of Alaska Seems way warmer than average for this time of year.

Submitted by Peter Longrich on Mon, 02/18/2019 - 03:37

Permalink

Hi Peter,

There's not enough heat from hydrothermal sources to explain sea surface temperature anomalies like the Pacific blob, and it would be difficult to explain the three-dimensional structure of these heat anomalies through hydrothermal sources.  Regarding the long-term trend, North Pacific sea surface temperatures, including in the Gulf of Alaska, have been rising over the past 50 years or so, so such warm anomalies are becoming more common.  (By the way, this is a nice site where you can do linear trend and other calculations if you have some familiarity with the layout.) 

 

Permalink
Overlooked is the finding that an annual forcing impulse likely provides the driver to ENSO. Can see this by doing an auto-correlation on the ENSO power spectrum https://geoenergymath.com/2019/02/16/autocorrelation-of-enso-power-spectrum/ This likely feeds into the predictability barrier

Submitted by Paul Pukite on Mon, 02/18/2019 - 14:02

Permalink
The latest update on the BOM shows an El Nino Watch (which is not consistent) and they may call El Nino for their side later in the autumn (spring here). If El Nino is here by US standards at the moment it will likely be marginal and short lived given the current SST temperatures hovering at the threshold or just below it, unless if could be a long sustained El Nino given the models (including the US model) are all over the place and should be cautioned early in the year. The SOI has not been consistent on the BOM side of things since the fall of last year and at times briefly reached the La Nina threshold late last year, even though the latest update shows the edge towards El Nino. I do wonder if there should be more consideration given to the SOI? Usually for them, values below -7 on a sustained basis indicate El Nino. Would like to know what the criteria is in the US for the SOI threshold on the negative side to be called El Nino?

Submitted by Graig Mellon on Tue, 02/19/2019 - 10:16

Permalink

Hi Graig,

Just to make sure all readers are clear about this, the NOAA and BOM criteria for an El Nino are not identical (see the BOM criteria here).  One of the differences is that BOM has a higher eastern tropical Pacific sea surface temperature threshold, so it is perfectly consistent for NOAA to declare borderline El Nino conditions while BOM does not. 

Regarding the SOI, NOAA does not have an explicit criterion like BOM does, but NOAA forecasters certainly consider the SOI and other atmospheric indicators.  As mentioned in this and previous blog posts, that was one of the main hold-ups for this event!  So to answer your question, there is no specific SOI threshold used by NOAA ENSO forecasters, but forecasters examine the SOI (among other metrics, including central Pacific OLR, Equatorial SOI in different datasets, lower and upper level winds), with a particular focus on how these metrics measure up with respect to their distribution for all previous El Nino events.  (The same is true if we have a potential La Nina event.)  

We make a final decision based on the preponderance of evidence.

Permalink

It is difficult to give a definitive answer to this question because El Nino types do not separate cleanly into canonical or Modoki types.  As this post describes, the location of maximum sea surface temperature anomalies varies rather continuously from east to west, so there is no clear separation between the two types.  With that said, and also consistent with this post, the weaker El Nino episodes tend to be centered more toward the central Pacific (Modoki-like), and this event is no exception.  For researchers who study the differences between canonical and Modoki El Nino, I'm pretty confident nearly all will characterize the current event as a Modoki event.  However, keep in mind that there are different methods for distinguishing ENSO "flavors," so we cannot expect universal agreement for all cases.  

Permalink
I have always wanted to learn about this topic but never found a website with this content. Please keep adding more of this content for me to read for me to read sincerely saleh goni

Submitted by Saleh goni on Sun, 02/24/2019 - 16:40

Permalink
It looks like the CFSv2 is picking up something for it's models to suggest a very warm El Nino for Winter 2019/20. This seems to contradict most other models and previous recent forecasts. Any idea what it is tracking to make it such an outlayer? Thanks!

Submitted by Matthew Stevenson on Tue, 02/26/2019 - 14:12

Permalink

Hard to say what the CFS is currently grabbing onto.  It is important though to remember that forecasts made through the spring are notoriously challenging, so I wouldn't pay much attention to the longer lead forecasts at this time.  

Submitted by mike.halpert on Thu, 02/28/2019 - 15:43

Permalink
How similar are current relevant world weather patterns to the year 2015? Can we see a repeat of the huge El Nino or an even bigger event at the end of this year?

Submitted by DG on Tue, 03/12/2019 - 18:18

Permalink
Is there any hope for relief from all the rain the northeast (I'm in southeastern New England, specifically RI), where all of the rain we have experienced for the past year is giving new meaning to "Swamp Yankee". Springs are nonexistent, the water works shut off for July/August 2018 with horribly oppressive humidity, turned on again in September and seemingly has not stopped - no snow to speak of this past winter. We are losing our collective minds.

Submitted by Allie on Sun, 05/05/2019 - 15:15

Permalink

I feel your frustration, as I write this on a cool and soggy Sunday in New Jersey.  I am not sure when the relief will come.  The CPC seasonal outlooks do not indicate a strong signal for precipitation in the northeast US, so they generally call for equal chances of above or below precipitation in the coming months.  We'll definitely continue to monitor any changes.  

Permalink
Trying to find reference to velocity of surface west to east current. Saw one reference at 60 cm/sec, but cannot re-find now. Help appreciated.

Submitted by Robert L Bunker on Tue, 06/04/2019 - 02:36

Permalink
Y don't weather channel don't show me the patterns,I can read them better than the other, hopefully thay bring them back to the weather station

Submitted by Thomas Bialaszewski on Thu, 07/18/2019 - 13:28

Permalink
what are the chance of a major hurricane out break in the tropical Atlantic hitting the gulf coast

Submitted by morris graves on Sat, 08/10/2019 - 01:10

Permalink

Making forecasts for where hurricanes may hit during a season is too difficult. However, the Climate Prediction Center did recently issue their updated forecast for the rest of the Atlantic hurricane season. Read all about it here. 

Submitted by tom.diliberto on Thu, 08/15/2019 - 08:41

Add new comment

About text formats